One of the most-awaited additions to Firefox on Android is extension support. Not only will it help the browser stand out even further from the sea of simple, Chromium-based browsers available on Android, but it will also allow for improving your Firefox browsing experience manifold. Mozilla had set a date for the launch of extensions on Firefox, and now, a selection of over 450 extensions is available for you to check out on your phone.
So, it finally looks like the bulk of extensions are now available to install.
See https://www.howtogeek.com/extensions-finally-landing-firefox-for-android/