I carry a Leatherman Charge +. The holster that came with it has an elastic “slot” on the side. It wasn’t quite big enough, so I stitched some nylon mesh in. The Leatherman holster now pulls fouble duty.

I haven’t seen anything like what you’re looking for on the market yet. Just a stretchy, grippy slot with a belt loop. It would be nice to have enough stiffness to make use of the pocket clip, too.