DuckDuckGo search option doesn't work by default
If you enter a search query into the address bar and select DuckDuckGo, the page will display the DuckDuckGo search bar but no results. If you reload the page, it notifies you that you must use the HTML-only version and links you there. This is confusing, and I'm sure most people don't figure out what the problem is. Even if you do figure it out, it's very inconvenient.
I imagine that a single-line change somewhere would allow Orfox to default to the HTML-only DuckDuckGo site instead of the normal one, which relies on JS. I'm planning on trying this myself if no one beats me to it, but I thought I'd mention it first because I've never worked with Mozilla projects or Android apps before.