I guess final update: I've decided to trade the car in. I can't own a vehicle with such questionable reliability. GM corporate didn't/wouldn't do the one thing I asked for, which was to provide me with a loaner or rental while they figured out my truck, that's all. They said I should drop it off, rent my own car, and submit for reimbursement, making sure to tell me that it wasn't guaranteed. That's just plain unacceptable to me. It isn't about the money, rental cars are super cheap right now, it's the principle.
The 2 dealerships here refused me a loaner when I called and asked before I went, so that was that.
I'm getting something else, I don't think I'll ever own another GM product.
0% APR over at Lexus right now due to covid if anyone is interested.