Nobara OS, Arch Linux and Pop!_OS beat Windows 11 by a slim margin in fps (delta 8) in Windows native games - Cyberpunk 2077, Forspoken, Starfield and The Talos Principle II. Windows 11 wins in Rachet & Clank.
ComputerBase’s testing was done on an all-AMD test rig, featuring a Ryzen 7 5800X (non-3D) and a Radeon RX 6700 XT.
Update: Windows 11 wins in one game.
Yes but the improvements and contributing Valve made to various packages in the Linux ecosystem and the kernel were all pushed upstream meaning any Linux distribution can benefit from them.