Earlier quoted context omitted.
I mean, we have that. It's called an imei and you can't change it. All that would be needed is for anyone selling a phone to provide the imei and some id to a govt service to assert that they are the current owner and intend to sell it for x price on y day. If you don't do this check and buy a phone, you're held liable if it is stolen. If you do, and it passes but later turns out to be stolen, automatically reimburse…
You can't change it, but you can find it inside the phone, no?
Have a central database of registered owners.
Allow current owner to assert that they own a given imei in a way that the buyer can check on said database.
Register the transfer of ownership during sale.