Apart from the many compatibility issues with all kinds of random games that can usually be fixed within an hour (but still cost me too much time), the biggest one is specific stuff like playing Assetto Corsa with mods in VR using a Logitech wheel. It's already a pretty hefty stack of things to keep working on Windows, but on Linux I cannot even get AC to start so I have no idea whether the rest will work.
I'm already fighting computers all day. When I get home tired the last thing I want to do is to fight the computer even more. I just want a game to start without issue. Even on my Steam deck I have regular hard crashes of the system in multiple games, and my PC is probably less supported due to the more random set of packages installed
Rollercoaster Tycoon Classic, if you feel like playing rollercoaster tycoon 1/2 on your phone. They slightly altered the UI to make it more touch friendly.