part-of-flake.nix

    defaultPackage.x86_64-linux = let
      nixosConfiguration = inputs.nixpkgs.lib.nixosSystem {
        modules = [
          (
            { config, lib, pkgs, ... }: {
              imports = [
                "${inputs.nixpkgs}/nixos/modules/profiles/installation-device.nix"
                "${inputs.nixpkgs}/nixos/modules/profiles/base.nix"
                "${inputs.nixpkgs}/nixos/modules/installer/sd-card/sd-image.nix"
              ];
              installer.cloneConfig = false;
              boot = {
                loader.grub.enable = false;
                loader.generic-extlinux-compatible.enable = true;
                consoleLogLevel = lib.mkDefault 7;
                kernelParams = ["console=ttyS0,115200n8" "console=ttyAMA0,115200n8" "console=tty0"];
                kernelPackages = pkgs.linuxPackages_latest;
                supportedFilesystems = lib.mkForce [ "btrfs" "f2fs" "vfat" ];
              };
              sdImage = {
                compressImage = false;
                populateFirmwareCommands = "";
                populateRootCommands = ''
                  mkdir -p ./files/boot
                  ${config.boot.loader.generic-extlinux-compatible.populateCmd} -c ${config.system.build.toplevel} -d ./files/boot
                '';
                #postBuildCommands = ''
                #  dd if=${pkgs.ubootLibreTechCC}/u-boot.gxl.sd.bin of=$img conv=fsync,notrunc bs=512 seek=1 skip=1
                #  dd if=${pkgs.ubootLibreTechCC}/u-boot.gxl.sd.bin of=$img conv=fsync,notrunc bs=1 count=444
                #'';
              };
              
              # Also tried this but results in infinite recursion
              # fileSystems = builtins.removeAttrs config.filesystems "/boot/firmware"
              fileSystems = lib.mkOverride 1 ({
                "/" = {
                  device = "/dev/disk/by-label/NIXOS_SD";
                  fsType = "ext4";
                };
              });
              
              nixpkgs = {
                config.allowUnfree = true;
                localSystem.system = "x86_64-linux";
                crossSystem = inputs.nixpkgs.lib.systems.examples.aarch64-multiplatform;
              };
            }
          )
        ];
      };
    in
    nixosConfiguration.config.system.build.sdImage;