I got it working on my Linux desktop with minimal issues (was crashing when I loaded into a map, was an easy system configuration fix after troubleshooting… I also use a more DIY distro so there are occasional quirks). I’m sure it will run fine on steam deck, I highly doubt Valve would have put the game out for beta before testing it on their own hardware
Valve has manually selected the game to be run with proton experimental under linux, and it works on my linux desktop. So it will probably at least run on Deck, but I don’t imagine it’s a very controller-friendly game. I have no idea about Mac.