You can make Python functionality available to your custom JavaScript via a bridge. The bridge goes both ways - your Python application can trigger JavaScript to run inside the visible windows too.
You can add application menus.
But if you want to give people a separate app experience it looks like a great option to me.
* pywebview hides its browser nature. Right click, text select, shortcut keys, swipe gestures etc are disabled by default.
* window manipulation functionality. Move, resize, minimize, maximize etc
* native file dialog support. These are more capable than browser's own file dialogs.
* native application menu
* with the new version you can get a full file path on file drag and drop. This is not possible in browser.
* two way Javascript-Python bridge. You can invoke Javascript from Python and Python from Javascript
* If Javascript is not your cup of tea, you can do quite a bit in pure Python.