Mozilla's GitHub now offers a version of Firefox for Android that is updated compared to the app available on the Google Play Store. Its most interesting attribute is an ability to add extensions to this mobile browser for the first time. There is only 1 add-on available at present, but the developer is confident there will be more soon.
https://www.notebookcheck.net/The-latest-Firefox-preview-for-Android-introduces-extension-support.457354.0.html