Unfortuately WebAuthn with the native keystores requires Bluetooth, which is a constant source of pain. That's a deal-breaker for me.
The server operator can choose to reject NFC, but the implementation/standard doesn't require that behavior.
Edit: Actually, I don't understand your question. Are you trying to authenticate on a PC using your phone as the security key? If so, I don't know how to do that. I just enroll Windows Hello and Face ID.