[txmx2000]

Or use a Google Voice number to setup 2FA on the same account. That way you can only ever login if you have a device on your person already logged in. If somehow you're away from technology long enough that all your devices are locked, use a printed backup code to unlock one.

[0xfeba]

Use Google Authenticator or any other time-based token app. Print out the private key, store in a safe. Also print out extra codes and also put in a safe.

[pascalxus]

But, if you use Google Voice number on your other Gmail account, they say it's not recommended because you can get locked out of both.

I think you can use Google Voice number on everything other than your main Gmail account.

So, to be extra safe, after you've set up your 2FA for gmail, make sure to change your recovery phone # to something other than your main telco or google voice number.

[txmx2000]

Same account. You can use the Google Voice number to 2FA its associated gmail account. A printed backup key will protect you from getting permanently locked out. But nobody will be able to login without physical access to your device or printed key.

This is how 2FA was meant to work. It should always require a physical device only you have access to. Otherwise it's just using 1FA two times.

[davchana]

Somewhere on YouTube somebody got locked from his google account while streaming live because of similar setup as your suggestion, Google 2fa codes to Google voice, and the look on the face when he realised it was hilarious. Not sure, but maybe he sorted it out somehow.