Arch with kde plasma desktop and dolphin file manager and gamescope is the ideal gaming setup because that is what the steamdeck uses and so is the best supported in terms of both bugfixes as well as performance due to valve devs working on that combo of software configuration. Preferably on amd gpu as that is also what steamdeck uses.

I would say dont get a deck if you have a pc. But if your pc is going unused you can sell it. And if you are without a pc then i can recommend a handheld pc ie steamdeck. Just my opinion, dont like wasting money on redundant hardware.

You can set timer to turn off display in desktop mode. So use desktop mode for long downloads with like 5min auto off timer on display while deck is downloading.

Inject uplay connect via protontricks.

https://youtu.be/1Lw7SwgnGZQ?feature=shared

Red alert 3.

you can set auto off display timer in desktop mode. Use desktop mode for long downloads.

Cod cold war doesnt work on steamos ie linux. You have to run it under windows 11. Call of duty black ops cold war, vanguard, modern warfare I\II\III all need windows 11.

try proton ge and report back here if it fixes it. It crashes on cutscenes due to some issues with codec for video playback. Proton ge is supposed to have a fix for it. Also try proton experimental if proton ge does not work.

Whats wrong with saints row 3 and 4 ?