[tialaramex]

I think it will stop pestering you for a phone number if you give it some neutral second factor like a Security Key ?

(Security Keys are actually way more anonymous than I'd even thought possible until I understood how they work, if you know Susie uses the same key for DropBox and GitHub, and you suspect Susie also uses this key for the account NumberOneSecretTrumpFan on GitHub, and then you steal all the account credentials from GitHub somehow, this doesn't end up being enough to verify that Susie has the same key as NumberOneSecretTrumpFan, nor is it enough to sign into Susie's DropBox account, and unless GitHub's data includes the backup passphrases or whatever it's not even enough to sign into GitHub as Susie, NumberOneSecretTrumpFan, or any other Security Key user...)

[icebraining]

I'm not sure how it is now, but for a long time Google required you to enable SMS auth (by giving your phone number) before you could enable TOTP or other 2FA methods.