nix: add plymouth

nix/modules/boot.nix

@@ -3,17 +3,32 @@
 # theming of grub
 
 {
-  boot.loader.grub = {
-    theme = pkgs.stdenv.mkDerivation {
-      pname = "hyperfluent";
-      version = "v1.0.1";
-      src = pkgs.fetchFromGitHub {
-        owner = "Coopydood";
-        repo = "HyperFluent-GRUB-Theme";
-        rev = "62e525ea2aa250e3f37669d68eb355b6cc997d64";
-        hash = "sha256-Als4Tp6VwzwHjUyC62mYyiej1pZL9Tzj4uhTRoL+U9Q=";
+  boot = {
+    loader.grub = {
+      theme = pkgs.stdenv.mkDerivation {
+        pname = "hyperfluent";
+        version = "v1.0.1";
+        src = pkgs.fetchFromGitHub {
+          owner = "Coopydood";
+          repo = "HyperFluent-GRUB-Theme";
+          rev = "62e525ea2aa250e3f37669d68eb355b6cc997d64";
+          hash = "sha256-Als4Tp6VwzwHjUyC62mYyiej1pZL9Tzj4uhTRoL+U9Q=";
+        };
+        installPhase = "cp -r nixos $out";
       };
-      installPhase = "cp -r nixos $out";
+    };
+
+    initrd.systemd.enable = true;
+
+    plymouth = {
+      enable = true;
+      theme = "rings";
+      themePackages = with pkgs; [
+        # By default we would install all themes
+        (adi1090x-plymouth-themes.override {
+          selected_themes = [ "rings" ];
+        })
+      ];
     };
   };
 }