Sometimes you learn the hard way. I try to use a Yubikey on as many services as possible, and when a service doesn't support U2F/Yubikeys, I resort to TOTP usin

Sometimes you learn the hard way. I try to use a Yubikey on as many services as possible, and when a service doesn't support U2F/Yubikeys, I resort to TOTP using the Google Authenticator app. I also backup the QR code seed image used to respawn the TOTP challenge response. I also make sure to grab any recovery code offered by the service so I can get back in, if my phone (which has the authenticator app on it) gets lost/stolen/damaged, or I lose my Yubikey. Google requires a phone number to register, but you can turn on U2F or TOTP 2FA and it won't ask for your number next time you login, and requires a Yubikey/TOTP instead.