Just to clarify my original comment: part of the reason I want to use reader mode is to make fonts of all pages a standard size, so I can read at night in low light, so I need more than just an ad blocker.
I could use an ipad for it, which I already own. The point is I want to use my android phone, and there is no good reason why I shouldn't be able (other than google doesn't let me, which isn't a good reason!)