Xalia (project I've been working on for about 2 years) is now out there in stable Proton. https://github.com/ValveSoftware/Proton/releases/tag/proton-9.0-2

This is an external program that adds gamepad controls to desktop apps (Linux, Windows, and Wine with some modifications in Proton). Currently only used for a few launchers, but hoping to expand this and have it usable in regular desktop environments.