I understand how FIDO works with yubikey: Yubikey device has a symmetric key and it uses appId, nonce and symmetric key to generate key pair for a website. And the device gives back public key and keyHandle (which can used to generate private key) to the RP.
But U2F works on chrome in Mac with Touchbar without yubikey. Does it mean MAC OS implemented U2F protocol? (But U2F doesn't work on safari!!!)
Who is generating and verifying the keyhandle in case of MAC?