feat: add plymouth option to bootloader

features/bootloader.nix

@@ -22,12 +22,16 @@
           ];
           default = "systemd-boot";
         };
+
+        plymouth.enable = lib.mkEnableOption "plymouth boot splash";
       };
 
       config = lib.mkIf cfg.enable (
         lib.mkMerge [
           {
             boot.loader.efi.canTouchEfiVariables = true;
+            # request the largest framebuffer uefi offers; plymouth inherits it
+            boot.loader.systemd-boot.consoleMode = "max";
           }
 
           (lib.mkIf (cfg.mode == "systemd-boot") {
@@ -41,6 +45,28 @@
               pkiBundle = "/var/lib/sbctl";
             };
           })
+
+          (lib.mkIf cfg.plymouth.enable {
+            # plymouth needs systemd-initrd to render the luks prompt cleanly
+            boot.initrd.systemd.enable = true;
+
+            # host is responsible for early-KMS so plymouth lands on the gpu driver,
+            # not simpledrm (e.g. hardware.amdgpu.initrd.enable on amd hosts)
+            boot.plymouth.enable = true;
+            stylix.targets.plymouth.logoAnimated = false;
+
+            boot.kernelParams = [
+              "quiet"
+              "splash"
+              "loglevel=3"
+              "rd.systemd.show_status=false"
+              "rd.udev.log_level=3"
+              "udev.log_priority=3"
+              "plymouth.force-scale=1"
+            ];
+            boot.consoleLogLevel = 0;
+            boot.initrd.verbose = false;
+          })
         ]
       );
     };