In firefox for android, it’s possible to enable desktop mode even in portrait orientation. That gives a screen which is, to say the least, “not very legible”:
but it does at a glance give a better representation (to mobile users) of what’s intended to be on the page, as seen by desktop users.
After that, it’s possible to use pinch zoom to make any part of the page legible. Still not very convenient, but may possibly be better then doing about 8 feet of scrolling to get to the rightmost column.