Can I use 2-1/2" metal studs to hang 1/2" drywall?
I'm not sure it would be worth making any stud that couldn't take drywall. For walls, the drywall creates an axial load on the stud which it should easily support. But interior walls must also support an arbitrary lateral load, 5 psf in the US. This combined with the axial load is what would do it in. The manufacturer of the studs should publish span tables that tell you the maximum height wall for which you can use each style of stud under varying conditions.

I've little doubt you can find a 2.5" stud that works, but I'm not sure the proper gauge. That's where the span tables come in. Sorry I can't give you a final answer. All I can say is there's reason for hope.