add core configuration

machines/nix/plymouth.nix

@@ -0,0 +1,31 @@
+{pkgs, ...}: {
+  boot = {
+    plymouth = {
+      enable = true;
+      theme = "bgrt";
+      #themePackages = with pkgs; [
+      # By default we would install all themes
+      #(adi1090x-plymouth-themes.override {
+      #  selected_themes = [ "bgrt" ];
+      #})
+      #];
+    };
+
+    # Enable "Silent Boot"
+    consoleLogLevel = 0;
+    initrd.verbose = false;
+    kernelParams = [
+      "quiet"
+      "splash"
+      "boot.shell_on_fail"
+      "loglevel=3"
+      "rd.systemd.show_status=false"
+      "rd.udev.log_level=3"
+      "udev.log_priority=3"
+    ];
+    # Hide the OS choice for bootloaders.
+    # It's still possible to open the bootloader list by pressing any key
+    # It will just not appear on screen unless a key is pressed
+    loader.timeout = 0;
+  };
+}