That was a fun read. It's interesting to think that they would leave it attached. Indeed, what could you do with that?
Did you find the unit that the wires go to? Then you could open that up and see what chips, sensors etc are in there.
Used car dealers install those as per bank requirement to find the car in case it needs to be repoed, if the customer finishes the payment it just stays in the car but the account is disabled (the dealer pays a monthly fee for nothing otherwise). So basically it’s sending location data to nobody.