[ijpoijpoihpiuoh]

You should have emergency backup keys as well printed on real paper. I have a set stored with our important files, and another in my nightstand. Having my phone stolen would be a damnable inconvenience, since that is my second factor -- although not via SIM, but via Google's in-app authentication. But it wouldn't be fatal.

[yellowapple]

I use andOTP, which is compatible with Google Authenticator and actually allows backing up the private keys (one of the key missing features of Google Authenticator, though maybe they've fixed that).

[retromario]

A good equivalent to andOTP on iOS is OTP Auth (backups, optional cloud syncs, it just works): https://apps.apple.com/us/app/otp-auth/id659877384