I feel that many of the answers here, which explain what could have been done beforehand to prevent this - are not very helpful to someone who's already locked out of their account.

It's never gonna be possible to 100% prevent any possibility that could cause loss of access to your 2FA. Some people will always fall through the cracks - whether that's due to their own negligence, lack of technical understanding or some algorithmic false positive doesn't really matter imho.

The real problem here is, that there's nothing that can be done to resolve something like that, AFTER it already happened. Not even if you were willing to pay for support to help you.

If you got good contacts, are famous, manage to go viral or something, you might be able to actually get help - but as a regular, boring, everyday person, you're just fucked. The only "advice" you are gonna get is: "you should have done this or that beforehand..." - and the obvious answer to that is: "I would have, had I only known!"

The only thing you can do, is post your story on HN and Twitter, and hope someone from Google reads it, and goes out of their way to actually help you - which obviously is AGAINST standard company procedure.