Google provides backup codes as last resort for 2-step verification enabled accounts for when there is no access of Mobile No. OTP or the optional/alternate email ID or even the Mobile Phone.
It is a very important feature which should be implemented immediately because moving emails to different folders everytime is annoying. You will not be copying Google by adding this feature because it is a necessity. Please, users need it dearly.
As updates keep making the app worse and worse. You can add new features but please do not expel old good features.