Military M12 holsters are cheap ~$20 at the surplus places, online or brick-&-mortar. The attachment set-up will allow the holster to be worn on your backpack belt, something other holsters will not.
I've been carrying my G20SF in a Bianchi M12 holster for years on hikes, backpacking trips, and scrambles. It stretched to fit the gun- so no drama there. Protecting the gun is pretty much what it was designed to do, and the military can be pretty hard on gear. I've taken a fall or two with mine, including one serious 50' tumble down a hillside, and my gun was secure and undamaged. I also didn't need to stop and clear the barrel afterwards.
EDIT to add: Another bonus with the M12 is you get a cleaning rod with the holster. That might come in handy.
I decided that concealed on a hiking trail was completely pointless and counterproductive.