"Login with X" is OAuth, not 2FA. 2FA is a great addition on top of a password per site. Neither a FIDO device nor an Authenticator app provides the site with a

"Login with X" is OAuth, not 2FA. 2FA is a great addition on top of a password per site. Neither a FIDO device nor an Authenticator app provides the site with any extra PI. Edit: SMS would give them your phone number, but SMS is a really bad 2FA and should not be used