My small wish is that FF on Android supports an intent that opens a URL in a new private tab. That way I'd be able to selectively open pages from HN, Reddit or other apps in private tabs—by the way of Tasker or Automate.
I looked a bit through FF code, and there's an intent to open an empty private tab, but not an address. Alas, with my lack of knowledge about data flow in an Android app, I'm not of much help so far.