

(played the demo) The game will attempt to install Microsoft Visual C++ runtime for you. But on next boot the game won't recognize it as being installed, thus it'll rerun the installer. If you select no, or cancel it, the game will simply close. Your only option is to uninstall, which then lets you run the game. Still runs fine without it, next boot install it again. I didn't care to tinker with it to avoid this.
Also it runs like a typical modern UE game sooooo. i mean maybe, it was something to do with proton.

All you need to do is enable Proton Experimental. That's it.

Ran probably just as well as it would on windows
Game ran perfectly fine with no performance issues apart from loading in very low quality textures even on an ssd first before loading in the higher quality ones but this is probably just because the game is in early access

The major pauses are very annoying, and although I did eventually get it working (mostly) it was still having some issues.
Issues with major freezing. This seemed to have lessened after the intro and tutorial level.
I don't know if the major issue is caused by either the tutorial, which pauses the game when showing the tutorial, or that it is a deeper level issue with the games' optimization. It is playable, but the first impressions would/could be pretty dire. When it runs well, it runs flawlessly, but the random freezing is very tedious and ruins the experience.

[Demo] Launches, but major performance issues
Frequent frame drops even on low quality settings, occasional freezing for several seconds

On steam deck wasn't able to launch game's Demo.
It starts, shows black screen for few seconds, then game splashcreen appears for few milli-seconds and then game crashes without any error message.