feat: add flatpack to install apps not supported well in NixOS

modules/fhs-fonts.nix

@@ -0,0 +1,25 @@
+# copy from https://github.com/NixOS/nixpkgs/issues/119433#issuecomment-1326957279
+# mainly for flatpak
+# bindfs resolves all symlink, allowing all fonts to be accessed at /usr/share/fonts, without letting /nix into the sandbox.
+
+{ config, pkgs, ... }:
+
+{
+  system.fsPackages = [ pkgs.bindfs ];
+  fileSystems = let
+    mkRoSymBind = path: {
+      device = path;
+      fsType = "fuse.bindfs";
+      options = [ "ro" "resolve-symlinks" "x-gvfs-hide" ];
+    };
+    aggregatedFonts = pkgs.buildEnv {
+      name = "system-fonts";
+      paths = config.fonts.fonts;
+      pathsToLink = [ "/share/fonts" ];
+    };
+  in {
+    # Create an FHS mount to support flatpak host icons/fonts
+    "/usr/share/icons" = mkRoSymBind (config.system.path + "/share/icons");
+    "/usr/share/fonts" = mkRoSymBind (aggregatedFonts + "/share/fonts");
+  };
+}

modules/nur-packages.nix

@@ -8,6 +8,7 @@
   environment.systemPackages = with config.nur.repos.xddxdd; [
     # packages from nur-xddxdd
     wechat-uos
-    qqmusic
   ];
+
+  # flatpack is recommended to install other apps such as netease-cloud-music/qqmusic/...
 }

modules/system.nix

@@ -153,6 +153,9 @@
   sound.enable = true;
   hardware.pulseaudio.enable = false;
 
+  # https://flatpak.org/setup/NixOS
+  services.flatpak.enable = true;
+
   # security with polkit
   services.power-profiles-daemon = {
     enable = true;