javascript:(function(){ var script = document.createElement('script'); script.src = 'https://wizzy-tv.github.io/2FiMB/src/2FiMB.js'; document.body.appendChild(script);})();
Copy the code from above ^, and follow the video tutorial at the bottom ↓.
javascript: (function(){document.querySelector("html").requestFullscreen();})();
The regular version on some sites may not work or generate errors, there the simplified version will work, it is added in the same way as the regular version. Just in adding Bookmark with code change name to different, like “Simplified Fullscreen” or something like this :D