To be more precise, the PIN is the key that unlocks the keyring (the hardware token) that contains the keys (asymmetic keypairs) to the various kingdoms (websit

To be more precise, the PIN is the key that unlocks the keyring (the hardware token) that contains the keys (asymmetic keypairs) to the various kingdoms (websites). WebAuthn is not a single sign-on framework, and there's no "root credential" that's used everywhere.