Have you seen the option to push the keyboard over to one side? Hold down the keyboard switcher button (you'll need at least two keyboards enabled) and there will be an option to move it over to one side or the other. (Native OS keyboard, iOS 12, I think.)
Also, the "reachability" feature is nice: double-tap (NOT click, just touch) the home button (or swipe down on the little bottom bar for iPhones lacking a home button) and the screen slides down half-way. I can reach the URL bar this way without moving my hand from typing position. (This does have to be enabled in settings.)
Side note: I've often wondered what it would be like to have only one hand to type with. What kind of a keyboard do you use? Any special software, etc.?