No case. No custom made motherboard that supports HDMI CEC. Lack of developers specifically developing around valve hardware like they did with the SteamDeck.

> Lack of developers specifically developing around valve hardware

Like what? The only "specific" thing that comes to mind are the boot animations and the Decky plugins (which should work with all SteamOS-like distros).

All of the optimizations, "Steam Deck" graphics settings, controller mapping support, Linux-friendly anticheat and more works on any Linux PC. Almost nothing is bespoke to the Deck, by design.