>Mobile firefox is OK, it simply feels like it's designed for a different person. For example even Chrome has "force reader mode" button.. Firefox does not.

I'm using Fennec from F-Droid, but I have a little document symbol on the URL bar I tap for reader mode. I guess the issue is it doesn't show on all sites then?

From my experience it's inconsistent and incredibly frustrating, but that's my experience with Firefox mobile overall.