There are several things it could be so the only thing you can do is get it up in the air and look. The thing is that many fair sized leaks will end up showing evidence in the location you described since whenever you drive anything leaking will tend to migrate backwards. So seeing evidence of a leak there doesn’t mean that the leak is there.
Its often hard to tell when everything is dirty (which it probably is), but reddish would likely be transmission fluid. Brownish would likely be engine oil. Power steering fluid could be different colors, but your GM recommendation probably comes as something roughly clear. Some cars are supposed to get trans fluid in the steering so it could be red also. Your coolant is probably Dex-Cool which is orange - but the coolant/water mix will be so thin you won’t likely see the color unless it is a puddle.