Your assumption about how datalogging works is incorrect.
In short, sensors almost never store local data which doesn’t even matter if those sensors are depowered. There is absolutely nothing to be afraid of here.
So yeah, sensors do not locally store data except in very rare and high-cost cases not found in basically any consumer electronics. There needs to be a datalogger or handoff to a datalogger of some variety. While the ECU or MCU of a vehicle logs data, there’s not a permanent memory of every action you’ve done with the car because it literally doesn’t have enough memory. Doubly so if some of the sensors such as GPS are physically unplugged or depowered as in my case.
So, no amount of malicious action from a dealer would extract location or even more basic data from a car. The only thing they’d see are the basics of the ECU or MCU which has been common for every car produced since OBD2 became… a thing.
I’ll also add that an easy solution to this is not to go to a corporate dealer (all Chevy dealers are shit anyway to be fair). While the independent mechanic might have to buy proprietary diagnostics from the manufacturer, they aren’t going to re-enable systems like GPS or telemetry if you tell them not to because they care about you coming back and thus have an incentive not to fuck you over.
Great, yet another case of: we want to build cars but “nobody” (a.k.a. everybody except piece of shit investors) wants reliable and inexpensive cars that aren’t spying on you.
So we need to unlock money from venture capital / rabid ai hype / insert sketchy bubble here, to build expensive luxury cars with fake self driving while selling all your data completely outside of your control.