Recent testing revealed that Arch Linux, Pop!_OS, and even Nobara Linux, which is maintained by a single developer, all outstripped Windows for the performance crown on Windows-native games. The testing was run at the high-end of quality settings, and Valve's Proton was used to run Windows games on Linux.
That depends which DLSS. In my testing DLSS 1 and 2 work fine in games that I tried, with recent Proton enabling it as well as ray tracing shouldnt require extra steps anymore (it was experimental and opt-in using environment variables). DLSS 3 with frame generation is known as no go yet and it’s unfortunately on NVIDIA to provide support for it as it’s very much locked down guarded proprietary stuff.