You should be able to get most games to work with some extra tinkering.
Got Armored Core running in HDR with this.
Also, I found it was enough to run the just the game in gamescope, no need to run the entirety of steam in a gamescope window. Just set the launch options for the game you want to enable HDR on.
This from the man who thinks he's "competing" with Valve?
Valve is figuring out how to run games they didn't even develop on Linux, while Epic complains it's too hard to do for even their own games...
That's rich.