Im wondering why Valve isnt working on a Anti-Cheat API for the Steam Deck? The RDNA2 has the necessary TPM features and a huge amount of work regarding remote attestation for Linux systems has been done in the past decade. They could make anti cheat on the Steamdeck more robust than any PC solution ever could since they have control of the full stack from the SoC to the software distribution (very close to what consoles are offering to developers).

PS: This could still allow for root acces for the end user, it would just mean you couldnt play some games while your custom kernel, kernel modules, system libraries are active. Easy enough to build a mechanism to switch back to a “secure” state if needed.