diff --git a/browser/components/syncedtabs/EventEmitter.jsm b/browser/components/syncedtabs/EventEmitter.sys.mjs
similarity index 91%
rename from browser/components/syncedtabs/EventEmitter.jsm
rename to browser/components/syncedtabs/EventEmitter.sys.mjs
index f39d8e9c90d2e..ed026dc173317 100644
--- a/browser/components/syncedtabs/EventEmitter.jsm
+++ b/browser/components/syncedtabs/EventEmitter.sys.mjs
@@ -2,12 +2,8 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-"use strict";
-
-var EXPORTED_SYMBOLS = ["EventEmitter"];
-
 // Simple event emitter abstraction for storage objects to use.
-function EventEmitter() {
+export function EventEmitter() {
   this._events = new Map();
 }
 
diff --git a/browser/components/syncedtabs/SyncedTabsDeckComponent.js b/browser/components/syncedtabs/SyncedTabsDeckComponent.sys.mjs
similarity index 82%
rename from browser/components/syncedtabs/SyncedTabsDeckComponent.js
rename to browser/components/syncedtabs/SyncedTabsDeckComponent.sys.mjs
index f7feb2f5cb85d..47571f789db77 100644
--- a/browser/components/syncedtabs/SyncedTabsDeckComponent.js
+++ b/browser/components/syncedtabs/SyncedTabsDeckComponent.sys.mjs
@@ -2,39 +2,13 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-"use strict";
-
-const { XPCOMUtils } = ChromeUtils.importESModule(
-  "resource://gre/modules/XPCOMUtils.sys.mjs"
-);
-
-const { SyncedTabsDeckStore } = ChromeUtils.import(
-  "resource:///modules/syncedtabs/SyncedTabsDeckStore.js"
-);
-const { SyncedTabsDeckView } = ChromeUtils.import(
-  "resource:///modules/syncedtabs/SyncedTabsDeckView.js"
-);
-const { SyncedTabsListStore } = ChromeUtils.import(
-  "resource:///modules/syncedtabs/SyncedTabsListStore.js"
-);
-const { TabListComponent } = ChromeUtils.import(
-  "resource:///modules/syncedtabs/TabListComponent.js"
-);
-const { TabListView } = ChromeUtils.import(
-  "resource:///modules/syncedtabs/TabListView.js"
-);
-let { getChromeWindow } = ChromeUtils.import(
-  "resource:///modules/syncedtabs/util.js"
-);
-const { UIState } = ChromeUtils.importESModule(
-  "resource://services-sync/UIState.sys.mjs"
-);
-
-let log = ChromeUtils.importESModule(
-  "resource://gre/modules/Log.sys.mjs"
-).Log.repository.getLogger("Sync.RemoteTabs");
-
-var EXPORTED_SYMBOLS = ["SyncedTabsDeckComponent"];
+import { SyncedTabsDeckStore } from "resource:///modules/syncedtabs/SyncedTabsDeckStore.sys.mjs";
+import { SyncedTabsDeckView } from "resource:///modules/syncedtabs/SyncedTabsDeckView.sys.mjs";
+import { SyncedTabsListStore } from "resource:///modules/syncedtabs/SyncedTabsListStore.sys.mjs";
+import { TabListComponent } from "resource:///modules/syncedtabs/TabListComponent.sys.mjs";
+import { TabListView } from "resource:///modules/syncedtabs/TabListView.sys.mjs";
+import { getChromeWindow } from "resource:///modules/syncedtabs/util.sys.mjs";
+import { UIState } from "resource://services-sync/UIState.sys.mjs";
 
 /* SyncedTabsDeckComponent
  * This component instantiates views and storage objects as well as defines
@@ -42,7 +16,7 @@ var EXPORTED_SYMBOLS = ["SyncedTabsDeckComponent"];
  * isolated and easier to test.
  */
 
-function SyncedTabsDeckComponent({
+export function SyncedTabsDeckComponent({
   window,
   SyncedTabs,
   deckStore,
diff --git a/browser/components/syncedtabs/SyncedTabsDeckStore.js b/browser/components/syncedtabs/SyncedTabsDeckStore.sys.mjs
similarity index 88%
rename from browser/components/syncedtabs/SyncedTabsDeckStore.js
rename to browser/components/syncedtabs/SyncedTabsDeckStore.sys.mjs
index 184f4cd6fcb46..392e0fea9977e 100644
--- a/browser/components/syncedtabs/SyncedTabsDeckStore.js
+++ b/browser/components/syncedtabs/SyncedTabsDeckStore.sys.mjs
@@ -2,13 +2,7 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-"use strict";
-
-let { EventEmitter } = ChromeUtils.import(
-  "resource:///modules/syncedtabs/EventEmitter.jsm"
-);
-
-var EXPORTED_SYMBOLS = ["SyncedTabsDeckStore"];
+import { EventEmitter } from "resource:///modules/syncedtabs/EventEmitter.sys.mjs";
 
 /**
  * SyncedTabsDeckStore
@@ -19,7 +13,7 @@ var EXPORTED_SYMBOLS = ["SyncedTabsDeckStore"];
  * will have `isUpdatable` set to true so the view can skip rerendering the whole
  * DOM.
  */
-function SyncedTabsDeckStore() {
+export function SyncedTabsDeckStore() {
   EventEmitter.call(this);
   this._panels = [];
 }
diff --git a/browser/components/syncedtabs/SyncedTabsDeckView.js b/browser/components/syncedtabs/SyncedTabsDeckView.sys.mjs
similarity index 90%
rename from browser/components/syncedtabs/SyncedTabsDeckView.js
rename to browser/components/syncedtabs/SyncedTabsDeckView.sys.mjs
index ccc96e066ba17..aacae71fa57fa 100644
--- a/browser/components/syncedtabs/SyncedTabsDeckView.js
+++ b/browser/components/syncedtabs/SyncedTabsDeckView.sys.mjs
@@ -2,14 +2,6 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-"use strict";
-
-let log = ChromeUtils.importESModule(
-  "resource://gre/modules/Log.sys.mjs"
-).Log.repository.getLogger("Sync.RemoteTabs");
-
-var EXPORTED_SYMBOLS = ["SyncedTabsDeckView"];
-
 /**
  * SyncedTabsDeckView
  *
@@ -18,7 +10,7 @@ var EXPORTED_SYMBOLS = ["SyncedTabsDeckView"];
  * rerender unless the state flags `isUpdatable`, which helps
  * make small changes without the overhead of a full rerender.
  */
-const SyncedTabsDeckView = function (window, tabListComponent, props) {
+export const SyncedTabsDeckView = function (window, tabListComponent, props) {
   this.props = props;
 
   this._window = window;
diff --git a/browser/components/syncedtabs/SyncedTabsListStore.js b/browser/components/syncedtabs/SyncedTabsListStore.sys.mjs
similarity index 97%
rename from browser/components/syncedtabs/SyncedTabsListStore.js
rename to browser/components/syncedtabs/SyncedTabsListStore.sys.mjs
index f5dc8cb4eab4e..67adcfdace911 100644
--- a/browser/components/syncedtabs/SyncedTabsListStore.js
+++ b/browser/components/syncedtabs/SyncedTabsListStore.sys.mjs
@@ -2,13 +2,7 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-"use strict";
-
-let { EventEmitter } = ChromeUtils.import(
-  "resource:///modules/syncedtabs/EventEmitter.jsm"
-);
-
-var EXPORTED_SYMBOLS = ["SyncedTabsListStore"];
+import { EventEmitter } from "resource:///modules/syncedtabs/EventEmitter.sys.mjs";
 
 /**
  * SyncedTabsListStore
@@ -17,7 +11,7 @@ var EXPORTED_SYMBOLS = ["SyncedTabsListStore"];
  * The state includes the clients, their tabs, the row that is currently selected,
  * and the filtered query.
  */
-function SyncedTabsListStore(SyncedTabs) {
+export function SyncedTabsListStore(SyncedTabs) {
   EventEmitter.call(this);
   this._SyncedTabs = SyncedTabs;
   this.data = [];
diff --git a/browser/components/syncedtabs/TabListComponent.js b/browser/components/syncedtabs/TabListComponent.sys.mjs
similarity index 95%
rename from browser/components/syncedtabs/TabListComponent.js
rename to browser/components/syncedtabs/TabListComponent.sys.mjs
index 4dac8a6020971..60b473675bc11 100644
--- a/browser/components/syncedtabs/TabListComponent.js
+++ b/browser/components/syncedtabs/TabListComponent.sys.mjs
@@ -2,11 +2,7 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-"use strict";
-
-const { XPCOMUtils } = ChromeUtils.importESModule(
-  "resource://gre/modules/XPCOMUtils.sys.mjs"
-);
+import { XPCOMUtils } from "resource://gre/modules/XPCOMUtils.sys.mjs";
 
 let log = ChromeUtils.importESModule(
   "resource://gre/modules/Log.sys.mjs"
@@ -18,8 +14,6 @@ XPCOMUtils.defineLazyModuleGetters(lazy, {
   OpenInTabsUtils: "resource:///modules/OpenInTabsUtils.jsm",
 });
 
-var EXPORTED_SYMBOLS = ["TabListComponent"];
-
 /**
  * TabListComponent
  *
@@ -29,7 +23,7 @@ var EXPORTED_SYMBOLS = ["TabListComponent"];
  * to state changes so it can rerender.
  */
 
-function TabListComponent({
+export function TabListComponent({
   window,
   store,
   View,
diff --git a/browser/components/syncedtabs/TabListView.js b/browser/components/syncedtabs/TabListView.sys.mjs
similarity index 98%
rename from browser/components/syncedtabs/TabListView.js
rename to browser/components/syncedtabs/TabListView.sys.mjs
index 85ab0544674cf..b50c2253a830b 100644
--- a/browser/components/syncedtabs/TabListView.js
+++ b/browser/components/syncedtabs/TabListView.sys.mjs
@@ -2,23 +2,13 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-"use strict";
-
 const lazy = {};
 
 ChromeUtils.defineESModuleGetters(lazy, {
   PrivateBrowsingUtils: "resource://gre/modules/PrivateBrowsingUtils.sys.mjs",
 });
 
-let { getChromeWindow } = ChromeUtils.import(
-  "resource:///modules/syncedtabs/util.js"
-);
-
-let log = ChromeUtils.importESModule(
-  "resource://gre/modules/Log.sys.mjs"
-).Log.repository.getLogger("Sync.RemoteTabs");
-
-var EXPORTED_SYMBOLS = ["TabListView"];
+import { getChromeWindow } from "resource:///modules/syncedtabs/util.sys.mjs";
 
 function getContextMenu(window) {
   return getChromeWindow(window).document.getElementById(
@@ -40,7 +30,7 @@ function getTabsFilterContextMenu(window) {
  * and triggers actions that may cause the state to change and
  * ultimately the view to rerender.
  */
-function TabListView(window, props) {
+export function TabListView(window, props) {
   this.props = props;
 
   this._window = window;
diff --git a/browser/components/syncedtabs/moz.build b/browser/components/syncedtabs/moz.build
index 710477a6458af..53451d81b67b4 100644
--- a/browser/components/syncedtabs/moz.build
+++ b/browser/components/syncedtabs/moz.build
@@ -9,14 +9,14 @@ BROWSER_CHROME_MANIFESTS += ["test/browser/browser.ini"]
 XPCSHELL_TESTS_MANIFESTS += ["test/xpcshell/xpcshell.ini"]
 
 EXTRA_JS_MODULES.syncedtabs += [
-    "EventEmitter.jsm",
-    "SyncedTabsDeckComponent.js",
-    "SyncedTabsDeckStore.js",
-    "SyncedTabsDeckView.js",
-    "SyncedTabsListStore.js",
-    "TabListComponent.js",
-    "TabListView.js",
-    "util.js",
+    "EventEmitter.sys.mjs",
+    "SyncedTabsDeckComponent.sys.mjs",
+    "SyncedTabsDeckStore.sys.mjs",
+    "SyncedTabsDeckView.sys.mjs",
+    "SyncedTabsListStore.sys.mjs",
+    "TabListComponent.sys.mjs",
+    "TabListView.sys.mjs",
+    "util.sys.mjs",
 ]
 
 with Files("**"):
diff --git a/browser/components/syncedtabs/sidebar.js b/browser/components/syncedtabs/sidebar.js
index da87f3e556bc9..bf65bd96d56c3 100644
--- a/browser/components/syncedtabs/sidebar.js
+++ b/browser/components/syncedtabs/sidebar.js
@@ -7,8 +7,8 @@
 const { SyncedTabs } = ChromeUtils.importESModule(
   "resource://services-sync/SyncedTabs.sys.mjs"
 );
-const { SyncedTabsDeckComponent } = ChromeUtils.import(
-  "resource:///modules/syncedtabs/SyncedTabsDeckComponent.js"
+const { SyncedTabsDeckComponent } = ChromeUtils.importESModule(
+  "resource:///modules/syncedtabs/SyncedTabsDeckComponent.sys.mjs"
 );
 
 var syncedTabsDeckComponent = new SyncedTabsDeckComponent({
diff --git a/browser/components/syncedtabs/test/xpcshell/test_EventEmitter.js b/browser/components/syncedtabs/test/xpcshell/test_EventEmitter.js
index 4836dc39da597..07f2a1b296899 100644
--- a/browser/components/syncedtabs/test/xpcshell/test_EventEmitter.js
+++ b/browser/components/syncedtabs/test/xpcshell/test_EventEmitter.js
@@ -1,7 +1,7 @@
 "use strict";
 
-let { EventEmitter } = ChromeUtils.import(
-  "resource:///modules/syncedtabs/EventEmitter.jsm"
+let { EventEmitter } = ChromeUtils.importESModule(
+  "resource:///modules/syncedtabs/EventEmitter.sys.mjs"
 );
 
 add_task(async function testSingleListener() {
diff --git a/browser/components/syncedtabs/test/xpcshell/test_SyncedTabsDeckComponent.js b/browser/components/syncedtabs/test/xpcshell/test_SyncedTabsDeckComponent.js
index 7433e5d1986f6..9162325081a0c 100644
--- a/browser/components/syncedtabs/test/xpcshell/test_SyncedTabsDeckComponent.js
+++ b/browser/components/syncedtabs/test/xpcshell/test_SyncedTabsDeckComponent.js
@@ -3,14 +3,14 @@
 let { SyncedTabs } = ChromeUtils.importESModule(
   "resource://services-sync/SyncedTabs.sys.mjs"
 );
-let { SyncedTabsDeckComponent } = ChromeUtils.import(
-  "resource:///modules/syncedtabs/SyncedTabsDeckComponent.js"
+let { SyncedTabsDeckComponent } = ChromeUtils.importESModule(
+  "resource:///modules/syncedtabs/SyncedTabsDeckComponent.sys.mjs"
 );
-let { SyncedTabsListStore } = ChromeUtils.import(
-  "resource:///modules/syncedtabs/SyncedTabsListStore.js"
+let { SyncedTabsListStore } = ChromeUtils.importESModule(
+  "resource:///modules/syncedtabs/SyncedTabsListStore.sys.mjs"
 );
-let { SyncedTabsDeckStore } = ChromeUtils.import(
-  "resource:///modules/syncedtabs/SyncedTabsDeckStore.js"
+let { SyncedTabsDeckStore } = ChromeUtils.importESModule(
+  "resource:///modules/syncedtabs/SyncedTabsDeckStore.sys.mjs"
 );
 const { UIState } = ChromeUtils.importESModule(
   "resource://services-sync/UIState.sys.mjs"
diff --git a/browser/components/syncedtabs/test/xpcshell/test_SyncedTabsDeckStore.js b/browser/components/syncedtabs/test/xpcshell/test_SyncedTabsDeckStore.js
index f909fc0faa9df..a75ded8c8a4c5 100644
--- a/browser/components/syncedtabs/test/xpcshell/test_SyncedTabsDeckStore.js
+++ b/browser/components/syncedtabs/test/xpcshell/test_SyncedTabsDeckStore.js
@@ -1,7 +1,7 @@
 "use strict";
 
-let { SyncedTabsDeckStore } = ChromeUtils.import(
-  "resource:///modules/syncedtabs/SyncedTabsDeckStore.js"
+let { SyncedTabsDeckStore } = ChromeUtils.importESModule(
+  "resource:///modules/syncedtabs/SyncedTabsDeckStore.sys.mjs"
 );
 
 add_task(async function testSelectUnkownPanel() {
diff --git a/browser/components/syncedtabs/test/xpcshell/test_SyncedTabsListStore.js b/browser/components/syncedtabs/test/xpcshell/test_SyncedTabsListStore.js
index 88ab29e355000..36138aace3634 100644
--- a/browser/components/syncedtabs/test/xpcshell/test_SyncedTabsListStore.js
+++ b/browser/components/syncedtabs/test/xpcshell/test_SyncedTabsListStore.js
@@ -3,8 +3,8 @@
 let { SyncedTabs } = ChromeUtils.importESModule(
   "resource://services-sync/SyncedTabs.sys.mjs"
 );
-let { SyncedTabsListStore } = ChromeUtils.import(
-  "resource:///modules/syncedtabs/SyncedTabsListStore.js"
+let { SyncedTabsListStore } = ChromeUtils.importESModule(
+  "resource:///modules/syncedtabs/SyncedTabsListStore.sys.mjs"
 );
 
 const FIXTURE = [
diff --git a/browser/components/syncedtabs/test/xpcshell/test_TabListComponent.js b/browser/components/syncedtabs/test/xpcshell/test_TabListComponent.js
index 4b98bb09b8da9..734baac2548f6 100644
--- a/browser/components/syncedtabs/test/xpcshell/test_TabListComponent.js
+++ b/browser/components/syncedtabs/test/xpcshell/test_TabListComponent.js
@@ -3,11 +3,11 @@
 let { SyncedTabs } = ChromeUtils.importESModule(
   "resource://services-sync/SyncedTabs.sys.mjs"
 );
-let { TabListComponent } = ChromeUtils.import(
-  "resource:///modules/syncedtabs/TabListComponent.js"
+let { TabListComponent } = ChromeUtils.importESModule(
+  "resource:///modules/syncedtabs/TabListComponent.sys.mjs"
 );
-let { SyncedTabsListStore } = ChromeUtils.import(
-  "resource:///modules/syncedtabs/SyncedTabsListStore.js"
+let { SyncedTabsListStore } = ChromeUtils.importESModule(
+  "resource:///modules/syncedtabs/SyncedTabsListStore.sys.mjs"
 );
 
 const ACTION_METHODS = [
diff --git a/browser/components/syncedtabs/util.js b/browser/components/syncedtabs/util.sys.mjs
similarity index 76%
rename from browser/components/syncedtabs/util.js
rename to browser/components/syncedtabs/util.sys.mjs
index 2d2ef7645e77e..7c93733c72a51 100644
--- a/browser/components/syncedtabs/util.js
+++ b/browser/components/syncedtabs/util.sys.mjs
@@ -2,11 +2,7 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-"use strict";
-
-var EXPORTED_SYMBOLS = ["getChromeWindow"];
-
 // Get the chrome (ie, browser) window hosting this content.
-function getChromeWindow(window) {
+export function getChromeWindow(window) {
   return window.browsingContext.topChromeWindow;
 }
diff --git a/browser/modules/webrtcUI.jsm b/browser/modules/webrtcUI.jsm
index 91fa54674f3ea..92b43a34f72ad 100644
--- a/browser/modules/webrtcUI.jsm
+++ b/browser/modules/webrtcUI.jsm
@@ -10,8 +10,8 @@ var EXPORTED_SYMBOLS = [
   "MacOSWebRTCStatusbarIndicator",
 ];
 
-const { EventEmitter } = ChromeUtils.import(
-  "resource:///modules/syncedtabs/EventEmitter.jsm"
+const { EventEmitter } = ChromeUtils.importESModule(
+  "resource:///modules/syncedtabs/EventEmitter.sys.mjs"
 );
 const { XPCOMUtils } = ChromeUtils.importESModule(
   "resource://gre/modules/XPCOMUtils.sys.mjs"
diff --git a/remote/shared/listeners/NetworkListener.sys.mjs b/remote/shared/listeners/NetworkListener.sys.mjs
index 7b19240309d11..d4d24f155edbb 100644
--- a/remote/shared/listeners/NetworkListener.sys.mjs
+++ b/remote/shared/listeners/NetworkListener.sys.mjs
@@ -2,19 +2,15 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-import { XPCOMUtils } from "resource://gre/modules/XPCOMUtils.sys.mjs";
-
 const lazy = {};
 
 ChromeUtils.defineESModuleGetters(lazy, {
-  NetworkEventRecord:
-    "chrome://remote/content/shared/listeners/NetworkEventRecord.sys.mjs",
+  EventEmitter: "resource://gre/modules/EventEmitter.sys.mjs",
   NetworkObserver:
     "resource://devtools/shared/network-observer/NetworkObserver.sys.mjs",
-});
 
-XPCOMUtils.defineLazyModuleGetters(lazy, {
-  EventEmitter: "resource://gre/modules/EventEmitter.jsm",
+  NetworkEventRecord:
+    "chrome://remote/content/shared/listeners/NetworkEventRecord.sys.mjs",
 });
 
 /**