gistfile1.txt

    # Get the non-free wireless firmware installed so the wireless chip
    # actually *works*.
    hardware.enableRedistributableFirmware = true;
    hardware.firmware = [
      (pkgs.stdenv.mkDerivation {
       name = "broadcom-rpi3plus-extra";
       src = pkgs.fetchurl
       { url = "https://raw.githubusercontent.com/RPi-Distro/firmware-nonfree/b518de4/brcm/brcmfmac43455-sdio.txt";
         sha256 = "0r4bvwkm3fx60bbpwd83zbjganjnffiq1jkaj0h20bwdj9ysawg9";
       };
       phases = [ "installPhase" ];
       installPhase = ''
       mkdir -p $out/lib/firmware/brcm
       cp $src $out/lib/firmware/brcm/brcmfmac43455-sdio.txt
       '';
       })
    ];