That’s not the target usecase for the deck or for cs2. It’s cool that it’s possible and really showcases how flexible and capable the deck is, but valve has no obligation to support or optimize for it.
Cs2 is quite optimized for a typical Windows gaming PC, aka the target platform. I get well over 300fps on my midrange build. Valve is putting a lot of extra work into proton configurations to get Windows games working well out of the box on the deck, it’s perfectly fine that they haven’t done that specific work for the deck yet, if at all.
I’m sorry to say but you’re an outlier. Most people with decks aren’t typically docking them, and even less are docking them as a desktop replacement. For me it’s a portable with the flexibility of easy couch coop but I never want to have to use a mouse and keyboard on it.
Controlling scope of supported systems to ones that are most commonly used is the smartest thing they could do. There’s a reason cs2 isn’t supporting consoles this time around and it’s telegraphing great things for the game this time. They aren’t making the same mistakes they had to correct with cs:go on launch.