use system type as host

systems/pi400/default.nix

@@ -0,0 +1,35 @@
+{
+  modulesPath,
+  lib,
+  nixos-hardware,
+  ...
+}:
+
+{
+  imports = [
+    (modulesPath + "/installer/scan/not-detected.nix")
+    nixos-hardware.nixosModules.raspberry-pi-4
+  ];
+
+  boot = {
+    initrd = {
+      availableKernelModules = [ "xhci_pci" ];
+    };
+    loader = {
+      generic-extlinux-compatible.enable = true;
+    };
+  };
+
+  fileSystems."/" = {
+    device = "/dev/disk/by-uuid/44444444-4444-4444-8888-888888888888";
+    fsType = "ext4";
+  };
+
+  hardware.raspberry-pi."4".fkms-3d.enable = true;
+
+  networking = {
+    useDHCP = lib.mkDefault true;
+  };
+
+  powerManagement.cpuFreqGovernor = "ondemand";
+}