Use Aegis. Also, using a backup email for Proton is not recommended since it is data that can be used to identify you. Use a recovery phrase for Proton instead. "If you forget your password, setting a recovery phrase allows you to reset your password so that you can access your Proton Account." "We recommend setting a recovery phrase to both access your account and decrypt your data."

Proton

Set account recovery methods in case you forget your Proton password | Proton

Set methods to recover your account if you forget your Proton password.