We add declarative flatpak file

modules/system/nixos/apps/flatpak.nix

@@ -0,0 +1,49 @@
+{
+  lib,
+  pkgs,
+  config,
+  ...
+}:
+with lib;
+let
+  grep = pkgs.gnugrep;
+  cfg = config.os.flatpak.apps;
+  flatpaks = [
+    "com.usebottles.bottles"
+    "io.github.flattool.Warehouse"
+  ];
+in
+{
+  options.os.flatpak.apps = {
+    enable = mkEnableOption "System gnome apps service";
+  };
+  config = mkIf cfg.enable {
+
+    services.flatpak.enable = true;
+    system.userActivationScripts.flatpakManagement = {
+      text = ''
+
+        ${pkgs.flatpak}/bin/flatpak remote-add --if-not-exists fedora oci+https://registry.fedoraproject.org
+
+        installedFlatpaks=$(${pkgs.flatpak}/bin/flatpak list --app --columns=application)
+
+        for installed in $installedFlatpaks; do
+          if ! echo ${toString flatpaks} | ${grep}/bin/grep -q $installed; then
+            echo "Suppression de $installed car il n'est pas dans la liste desiredFlatpaks."
+            ${pkgs.flatpak}/bin/flatpak uninstall -y --noninteractive $installed
+          fi
+        done
+
+        for app in ${toString flatpaks}; do
+          echo "Vérification que $app est installé."
+          ${pkgs.flatpak}/bin/flatpak install -y flathub $app
+        done
+
+        ${pkgs.flatpak}/bin/flatpak uninstall --unused -y
+        ${pkgs.flatpak}/bin/flatpak update -y
+
+      '';
+    };
+
+  };
+}

modules/system/nixos/apps/gnome/apps.nix

@@ -15,21 +15,9 @@ in
   config = mkIf cfg.enable {
 
     environment = {
-      systemPackages =
-        with pkgs;
-        [
-          # Gnome media apps
-          loupe
-          papers
-          celluloid
-
-          resources
-          gnome-logs
-        ]
-        ++ [
-          # Gnome files explorer
-          nautilus
-        ];
+      systemPackages = with pkgs; [
+        nautilus # Gnome files explorer
+      ];
     };
 
     services.gvfs.enable = true; # SMB, FTP, ... access