How about Yubikey?
[supports one-factor, 2FA, and multi-factor hardware authentication].
YubiKey is a hardware security key that makes 2FA authentication as easy as possible, and instead of entering the generated code into the app on your phone, you simply press a button
(especially since Coinbase or Gemini are compatible with this and other security keys). Instead of having several smartphones with an authentication application, you can connect up to 5 devices Yubikay to Coinbase at the same time, so you will have a lot of backup keys for all occasions,
(but it's better to buy them on Black Friday). If you are really paranoid
[say, you operate with huge amounts of money], then think about a combination of a hardware key and an authentication application on a iphone.