This applet is an implementation of the Ledger Wallet Hardware Wallet described at https://ledgerhq.github.io/btchip-doc/bitcoin-technical.html and emulating an NFC Forum Type 4 tag to display the second factor.
It is compatible with the core API with a few limitations if not using a proprietary API to recover public keys - the public key cache needs to be provisioned from the client side
A sample modification of the client API to do that transparently will be available shortly
For any question or commercial licensing, reach us at [email protected]