Offline "backup" codes
Similar or exactly how Google provides 10 Backup Codes for 2FA. It would be incredibly helpful to use Proton Services while on a customer site, or at a location where personal devices are disallowed.
3
votes

-
[Deleted User] commented
If you mean those little strings of text that allow you to recover your account if you cannot accesses 2FA then Proton already has those. Whenever you enable 2FA on an account it will let you download them.