Still usable with FIrefox for Android if you use Fennic (from the F-Droid app store) or Firefox Nightly version, then follow these official steps:

https://blog.mozilla.org/addons/2020/09/29/expanded-extension-support-in-firefox-for-android-nightly/

And thank god because this extension is the only thing that makes reddit on a mobile browser bearable for those occasions when I need to use it.