On all OSes, you need to use the beta or "next" version of Proton. In your games library, search for "Proton", right-click on the "5.0" entry, and opt-in to the beta in the "next" branch. If you do not do this, then nothing will work.
On NixOS, install amdvlk by adding the following to your configuration.nix. For more information, refer to the relevant nixos/nixpks pull request. You can test this with vulkaninfo or vkcube, both of which should just work. If you do vulkaninfo | grep GPU, then on radv you see (AMD RADV ...) but on amdvkl you see (Radeon ...).
hardware.opengl.extraPackages = [ pkgs.amdvlk ];
environment.variables.VK_ICD_FILENAMES = "/run/opengl-driver/share/vulkan/icd.d/amd_icd64.json";Some believe the launcher works with protontricks 1086940 dotnet48, but that did not work for me. Therefore, I needed to *[refer to this ValveSoftware/Proton issue](ValveSoftware/Proton#4243