I have submitted my add-on (unlisted) and it is approved and I can download and install the XPI on my laptop. I have found lots of instructions for how to get this on my Android device, but it all seems to be out of date and nothing works.
For example this post links an old Reddit thread that describes Firefox menu items that no longer exist.
When I submitted the add-on there was a checkbox to say if it was tested on Android, so I think it must be possible!