I did try to install this add-on https://addons.mozilla.org/en-CA/firefox/addon/old-reddit-redirect/ but the installation button is grayed out :(
2 points
Firefox on Android only allows a select few add-ons unless you install a nightly version or something. I don’t do it myself but it should be easy to Google
1 point
1 point
On Firefox Beta/Nightly you can enable Debugging Menu, by going to About on settings, and tapping the logo 3 times.
There you can add Custom Add-on collection.
You can create developer account on Mozilla, and add any add-on that you want.
1 point