Hello and welcome!
I think you'd be fine with any power steering fluid that does not say for "winter climates" or for "imports" like Honda, Toyota, etc. As long as it says compatible with GM vehicles, you should be fine. It doesn't have to be ACDelco. It's made by another supplier like Mobil or Petro Canada as they don't have their own refineries. They are just relabelers.
So in summary, use any quality brand power steering fluid that says "Compatible with GM vehicles".