If only Google would let you pay for support. Someone unintentionally locked out of their account would probably happily pay $50 to get back in.
I had to deal with this a while back because TFA was enabled on my account and I got a new phone and number at the same time so my login options were all broken, and the recovery flow didn't work for the same reasons. Thankfully this was a Google for Work account so there was a way for me to prove domain ownership and they restored my access. If this had been my personal Gmail account (not attached to the domain), I would have had no way to recover it, partly because I couldn't prove ownership so easily, but mostly because they have basically no support for personal accounts.
They do let you do that. For $60 a year, you can have 24x7 phone/email support via their Google Apps platform. No restriction on it needing to be for work AFAIK.
I think that's just a convenience thing. I'm fairly sure you can sign up without and they'll still give you support. I've had Google Apps for years now and it's been good.
I had to deal with this a while back because TFA was enabled on my account and I got a new phone and number at the same time so my login options were all broken, and the recovery flow didn't work for the same reasons. Thankfully this was a Google for Work account so there was a way for me to prove domain ownership and they restored my access. If this had been my personal Gmail account (not attached to the domain), I would have had no way to recover it, partly because I couldn't prove ownership so easily, but mostly because they have basically no support for personal accounts.