With Firefox 122+ (& Android 10+) you can still install/sideload this add-on by downloading xpi-file of latest release from GitFlic (with automatic add-on updates) when you enable the debug menu (settings > about > tap Firefox logo 5 times > return to settings): you’ll get new menu item Install extension from file
Does this work on mobile Firefox?
Yes, it does. There are instructions in the readme.
Thank you. I’ll take a look.
Edit: instructions: