When big game hunting, I'm usually packing my suppressed 22lr pistol on a leg holster. Takes practice to be accurate with it out to longer ranges with subsonic ammo. I always try to get as close as I can. I just don't want to make noise if I'm elk hunting.
Otherwise, I have a breakdown Savage 42 Takedown that I sometimes carry in my backpack. That thing is great for grouse. Not a pistol, but breaks down to 20" length and comes with carry bag. I usually shoot subsonic 22lr, or switch to 410 if I'm OK making some noise. It's a surprisingly accurate gun. Much easier to hit a grouse at distance with it than a pistol.