It would be a weird and illegal thing for a dealer to claim TSB work that was not done. They get paid by GM to do these and lots of times the replaced parts have to be returned to GM.
What is it you are worried about? Your question is very open ended.
nothing specifically I am worried about. just generally. I was going though some TSBs, such as #N202321230, heater hose not aligned properly. The TSB states: "Whenever a vehicle subject to this service update enters your vehicle inventory or is in your facility for service in the future, and the vehicle is still covered under the New Vehicle Limited Warranty, you must take the steps necessary to be sure the service update correction has been made before selling or releasing the vehicle."
Pretty simple TSB. That is just one example. There are A LOT of TSBs on these vehicles, and so was wondering if it was possible to tell if the dealer did all the "checks" while it was on lot, before it was sold to me. I am sure dealers have a lot going on so it wouldn't surprise me if they missed some of these. Just not sure the process when a new vehicle is on lot waiting for sale. I kind of always assumed it just sat there. There are quite a few new vehicles on the lot at any given time. So I just wouldn't assume that they managed to check all of them for the TSBs like this. After all, not all the TSBs are checks like this, some come into play only if a customer has a specific complaint (like the one I dealt with: PIE0592 cameras showing intermittently or not at all).
I am guessing the first letter indicates something about the necessity of the TSB. Given all of the TSBs it just would be nice if there was a way to check what has or hasn't been done on a vehicle.