Samtime tries out a Fairphone 4 running Ubuntu Touch and it seemed pretty fine. Noted issues were the second camera not working, GPS/Map app being a bit weird, and imo, the screen showing all the apps you have open is terrible. But with the reg app store and waydroid, I think it could be almost managable to use.
My mom is a battery life fiend though, so that part she won't let go of. What's your thoughts?