> ENABLE TWO-FACTOR AUTHENTICATION
More than this: use a password manager that has 2FA built-in and use THAT as your google account MFA.
The "easy" MFA with gmail involves approving new login attempts with an existing authed app present. But without an activated phone or other authed devices present, there is no way to authenticate to the GMail app to receive email.
Apple replaced the back of my iPhone after I dropped it. They do this by putting a new phone onto your screen and then tossing your old phone along with its activation status. ESIM, so no way to activate it without the old phone (which is now screen-less and inoperable). I could not even activate my phone because TMobile required a OTP from my email which I could not access. (Apple did not warn me about this at all btw.)
I was essentially 100% locked out of my account and unable to use voice, data, or access my google account until I could find a TMobile store to get a new SIM card and then use live-chat on the TMobile website to relay the one-time code from my laptop which thankfully was still authed. To say I was panicking about not being able to access anything was an understatement.
Lesson learned: use an MFA mechanism that doesn't require an activated phone since you can't activate your phone without having access to your phone. Now I have my MFA details in 1Password which is restored as a part of iCloud backup.