This is literally why I said it would sound suspicious. Most people wouldn't be able to tell. Which is why I said you'd need to provide some kind of sufficient proof of your identity (or some adequate alternative) to address their fears.

If you are desperate, you might have to just trust that person your login/password, ask them to login to your acc and change/add phone number.

Fantastic suggestion! Definitely a great option if they're willing to take the risk.

If not, another one I was thinking was asking them to meet at their local police department and looping in an officer into the story or something. Different things work for different folks so they'd have to get creative to find the right solution.

Ah yes, the old playbook of using police for free instead of running a customer support department in your trillion dollar company.

There might be an opportunity here for a trusted, legally bound third party to validate people identities and ensure smooth transfer of ownership...

Oh wait, I believe these are called notary offices in meatspace!

(tangent: at some point I thought that maybe notaries could sign one's PGP key instead of relying on rare/non-existent signing parties)

dammit I love your usename

Does google allow to have same phone number listed as 2FA on multiple google accounts?

Yes.

I would be very wary of associating multiple Google accounts together. You don't need a single mistake from your personal account to cause a closure of your business account - and Google is known to do that. I recently had "nicer" auto_corrected to "ni66er" (Android keyboard swiping) even though I've never used that racial slur in my life. I could see how that might set off a chain reaction leading to account closure.