You can’t weed out the exporters. If you need to sell your C8 before the clock runs out on the don’t sell clause, your only real solution is to sell or trade back to a dealer. Actually this is only true in if you want to buy another GM product.
Except selling a used car usually requires a lien check and for the car to be lien free. No exporter, or frankly most any other buyer, will buy a used vehicle with a lien. I guess that stops it from being exported but also stops it from being sold.
GM has to follow the same rules of course. They take Canadian taxpayers money and build a plant in China. Can't allow you to take advantage of the "Mother Company". They are quick learners!
The agreement I signed was 1 year or 12k mileage whichever came first. I have 5 months left. I knew the deal and will honor my commitment. Easy as I have no interest in selling at this point.