> It’s possible, although I don’t know if Microsoft allows users to roll back from “passwordless” and discoverable keys.
I don't know about Microsoft specifically, but it's possible to register the same FIDO2-capable security key with a service as both a passkey and a U2F token.
I don't know about Microsoft specifically, but it's possible to register the same FIDO2-capable security key with a service as both a passkey and a U2F token.