Do you still have the phone physically? And it has a password that is why you can't access it?

What I think is there are phone technicians that can able to disable passwords without data erased. So that you can able to access all data and apps from your uncle's phone if you hire a technician to disable the phone password. That's the only thing that I think before you recover the 2FA from Coinbase because there is a big possibility it will ask for a KYC if you are going to recover the 2FA.

Let me ask if how many characters are in those "keys"? it might be a secret key for the 2FA app and if that's the secret key you can use it to recover the 2FA of that Coinbase wallet.