1. Ford and GM are multi-national companies. They have been huge in a lot of overseas places for a long time. In some places I've been, there is a lot of status in owning a big "American" car, regardless of where it is made.
2. Years ago, the Toyota I bought had more American made parts and American assembly that either the Ford or Chevy I previously bought. I was supporting American jobs by buying Toyota instead of Ford or Chevy. I'll mention that the Toyota was much better made and lasted a lot longer than either the Ford or Chevy I had. Americans can make good cars if they are designed right.
I don't know the details of that proposed deal. My guess is that GM is trying to use it to get a bigger inroad into the Chinese market, probably by creating a "Chinese Owned" subsidiary or something like that to get around the "Chinese Content" requirements.
I seriously doubt that will help jobs here though. I expect any GM cars sold to the Chinese through that deal will be made and assembled in China. The best I would hope is that the profits GM might make through that deal might be used to help keep Pineapple Mama's GM plant afloat in the US.