Owens Corning 705 install question / option
I’ll totally admit that this is guesswork, but I think OC is better suited for surface/open air application. The frequencies it’s going to help the most with will reflect off the outer layer of drywall, in my opinion. You’ll still need to surface treat the walls.
That said I’ve heard people doing something similar to what you say in order to soundproof between living units, but with a rubber middle layer, not OC. Drywall, then channel with rubber mats in between, then mount drywall to the channel over the rubber.