Firefox for android only.
I will change this review if this addon starts to work on mobile. One star for visibility and for not working on mobile.

Problems.
1. The black rss icon shows up to the address bar but nothing happens when pressed.
2. Addon is not listed in the hamburger menu.
3. Addon's option's page's buttons do nothing on mobile when pressed.
4. Not usable in current state.

If not possible to make this addon work on mobile then add a disclaimer to addon's description or something.