Valve has published the latest news regarding the Steam Deck console. The material states that at release the platform will support projects that have Easy Anti-Cheat (EAC) or BattleEye anti-cheat systems installed.
Both software protect game projects (preferably used in online games) from the use of prohibited software that allows you to gain an unreasonable advantage over other players. Usually anti-cheat forbids running mods, under which most of the cheat programs disguise themselves.
Thus, you can be sure that with the help of Steam Deck it will be possible to run most of the games protected by the corresponding software.