wayland: add module

modules/modules.nix

@@ -417,6 +417,7 @@ let
     ./systemd.nix
     ./targets/darwin
     ./targets/generic-linux.nix
+    ./wayland.nix
     ./xresources.nix
     ./xsession.nix
     ./misc/nix.nix

modules/wayland.nix

@@ -0,0 +1,24 @@
+{ lib, ... }:
+
+{
+  meta.maintainers = [ lib.maintainers.thiagokokada ];
+
+  options = {
+    wayland = {
+      systemd.target = lib.mkOption {
+        type = lib.types.str;
+        default = "graphical-session.target";
+        example = "sway-session.target";
+        description = ''
+          The systemd target that will automatically start the graphical Wayland services.
+          This option is a generalization of individual `systemd.target` or `systemdTarget`,
+          and affect all Wayland services by default.
+
+          When setting this value to `"sway-session.target"`,
+          make sure to also enable {option}`wayland.windowManager.sway.systemd.enable`,
+          otherwise the service may never be started.
+        '';
+      };
+    };
+  };
+}