I don't remember having to do that on my "Steam Machine" which is a desktop running NixOS. This is most of my "VR" module:

    environment.systemPackages = with pkgs; [
      iw
    ];

    nixpkgs.config.allow32Bit = true;

    # Steam Frame dongle requires a region be set to work
    boot.extraModprobeConfig = ''
      options cfg80211 ieee80211_regdom=ES
    '';

    # SteamVR requires CAP_SYS_NICE, this patch allows it to have it
    # WARNING: This allows any application to create high priority contexts
    boot.kernelPatches = [
      {
        name = "amdgpu-ignore-ctx-privileges";
        patch = pkgs.fetchpatch {
          name = "cap_sys_nice_begone.patch";
          url = "https://github.com/Frogging-Family/community-patches/raw/master/linux61-tkg/cap_sys_nice_begone.mypatch";
          hash = "sha256-Y3a0+x2xvHsfLax/uwycdJf3xLxvVfkfDVqjkxNaYEo=";
        };
      }
    ];

    # SteamVR environment variables
    environment.sessionVariables = {
      # Force XCB platform for SteamVR under Wayland (prevents Qt Wayland issues)
      QT_QPA_PLATFORM = "xcb";
    };

It's been working with my Frame perfectly.