I know the remote aspect is important to you, but having done this exact switch (general backend services dev -> backend dev for a big game company) this requirement is almost certainly going to hold you back. The field is bleeding jobs and there are plenty of people who will go ass-in-seat 5 days a week. Outside of that, there are a surprising amount of roles that generalist SWEs fit into that don't require any experience. It's been a very comfortable foot-in-the-door for myself, at least.
I use KDE Plasma and it worked just fine. In fact all of my games (including Arc Raiders) are working just fine on Proton 10, maybe running slightly worse. The only issue I've run into is getting battle.net working through Lutris; I ended up manually installing it through Proton 10 on Steam and it worked just fine. Wish I made the switch earlier.