It works just as described. I would second the motion for more controls, especially one to auto advance to the next picture.

Not bad, but needs extra control and options.
I was searching for Web Slide Show add-on subsitution. https://addons.mozilla.org/ru/firefox/addon/web-slide-show/
So, it might be good to add "auto next image" and "fullscreen view" options.
Also, the addon's icon isn't visible with dark themes - https://i.imgur.com/xKhmJZ5.png