Works pretty well for me. I just have this config:

  # Sadly we can't easily install steam on a per-user basis, because installation
  # requires touching a lot of system libraries, etc.
  programs.steam = {
    enable = true;
    remotePlay.openFirewall = true; # Open ports in the firewall for Steam Remote Play
    dedicatedServer.openFirewall = true; # Open ports in the firewall for Source Dedicated Server
  };

I’m using Sway on an Nvidia RTX 4080 Super. It’s important to be on the latest driver. I’m still waiting for Sway to merge support for DRM explicit sync objects, but until then, gaming still works fine with the occasional artifacts from lack of synchronization with the kernel.

If by chance you need a specific Nvidia driver, you can configure that like so:

  hardware.graphics.enable = true;
  hardware.nvidia = {
    package = config.boot.kernelPackages.nvidiaPackages.stable;

    # More versions readily available for downgrading.
    # package = config.boot.kernelPackages.nvidiaPackages.mkDriver {
    #   version = "535.154.05";
    #   sha256_64bit = "sha256-fpUGXKprgt6SYRDxSCemGXLrEsIA6GOinp+0eGbqqJg=";
    #   sha256_aarch64 = "sha256-G0/GiObf/BZMkzzET8HQjdIcvCSqB1uhsinro2HLK9k=";
    #   openSha256 = "sha256-wvRdHguGLxS0mR06P5Qi++pDJBCF8pJ8hr4T8O6TJIo=";
    #   settingsSha256 = "sha256-9wqoDEWY4I7weWW05F4igj1Gj9wjHsREFMztfEmqm10=";
    #   persistencedSha256 = "sha256-d0Q3Lk80JqkS1B54Mahu2yY/WocOqFFbZVBh+ToGhaE=";
    # };
    # package = config.boot.kernelPackages.nvidiaPackages.mkDriver {
    #   version = "550.40.07";
    #   sha256_64bit = "sha256-KYk2xye37v7ZW7h+uNJM/u8fNf7KyGTZjiaU03dJpK0=";
    #   sha256_aarch64 = "sha256-AV7KgRXYaQGBFl7zuRcfnTGr8rS5n13nGUIe3mJTXb4=";
    #   openSha256 = "sha256-mRUTEWVsbjq+psVe+kAT6MjyZuLkG2yRDxCMvDJRL1I=";
    #   settingsSha256 = "sha256-c30AQa4g4a1EHmaEu1yc05oqY01y+IusbBuq+P6rMCs=";
    #   persistencedSha256 = "sha256-11tLSY8uUIl4X/roNnxf5yS2PQvHvoNjnd2CB67e870=";
    # };

    modesetting.enable = true;
    nvidiaSettings = true;
  };

  # Weird that "xserver" is here when we are using Wayland. But this is required
  # to install the NVIDIA driver.
  services.xserver.videoDrivers = [ "nvidia" ];