I've been kicking around an idea for an in-VR LFG app.
When you fire up steamvr, you press the system button and go to the LFG tab, pick several MP games you'd be willing to play and then play single player VR games for a while. When one of the games you're interested in gets enough people who are also interested, it shows a popup in whatever game you're playing that says your group is ready and you should launch the MP game.
After everyone is in the game it would be on them to set up the match, maybe with the app designating one of the group as the host. It could also theoretically automatically launch the MP game after a countdown or w/e.
I think it could help a lot of these near-zero player count games. I've done some proof of concept stuff with the overlays and getting info from steam so I think it's pretty doable, I would just need to get on my ass and do it.