A privacy podcast I listen to recently said that, for now anyway, it's possible to use a temporary/burner phone to do the initial SMS-based signup, then switch

A privacy podcast I listen to recently said that, for now anyway, it's possible to use a temporary/burner phone to do the initial SMS-based signup, then switch to app-based 2FA on a different phone, and then delete the phone # associated with the temporary/burner phone (as you said).