As much as I love my steam deck and the os, I do wish it was slightly easier to install third party games.
I know it's not hard and I've installed plenty, but like it's so incredibly easy with steam that it's made me lazy to even install games I already have on gog
It's not Linux or SteamOS, but both Epic and CD Projekt don't support their store client apps and launchers on Linux sadly, such we have to use unofficial ones such as Heroic Game Launcher