Test out NixOS/nixpkgs#282022

I had to run `sudo sgdisk --typecode=2:4F68BCE3-E8CD-4DB1-96E7-FBCAF984B709 /dev/nvme3n1`
in order to cause the right partition type code to be applied to the correct partition,
so that `systemd-gpt-auto-generator` would detect it at boot time.

boot.nix

@@ -60,16 +60,19 @@ in
   environment.systemPackages = [ pkgs.tpm2-tools ];
 
   boot.swraid.enable = false;
-  fileSystems = {
-    "/" = {
-      device = "/dev/disk/by-uuid/d5a0f038-5839-44e1-ad49-5edd00d7f81e";
-      fsType = "ext4";
-    };
 
-    "/boot" = {
-      device = "/dev/disk/by-uuid/0D2C-FF36";
-      fsType = "vfat";
-    };
+  # Test out nixos/nixpkgs#282022 (gpt-auto-root)
+  boot.initrd.gptAutoRoot.enable = true;
+  boot.initrd.supportedFilesystems = ["ext4"];
+
+  #fileSystems."/" = {
+  #  device = "/dev/disk/by-uuid/d5a0f038-5839-44e1-ad49-5edd00d7f81e";
+  #  fsType = "ext4";
+  #};
+
+  fileSystems."/boot" = {
+    device = "/dev/disk/by-uuid/0D2C-FF36";
+    fsType = "vfat";
   };
 
   swapDevices = [ ];

flake.nix

@@ -3,7 +3,8 @@
   nixConfig.commit-lockfile-summary = "flake.nix: update the lockfile";
 
   inputs = {
-    nixpkgs.url = "github:nixos/nixpkgs";
+    # Test out nixos/nixpkgs#282022
+    nixpkgs.url = "github:elvishjerricco/nixpkgs/gpt-auto-root";
 
     # Empty flake for making complex flake dependencies stop dead.
     empty.url = "path:./empty.nix";