I've been using Kivy. But decided if I did native, I'd only support iOS. Mostly because I don't want to go down the rabbit hole of having to support some random Android device.

So I'm looking at learning more about Swift and that ecosystem someday. I don't know C# but I certainly see Xamarin as an upgraded version of Kivy.. obviously going from a free platform to a paid one. It's something I've keeping my eye on for quite some time.

If I ever find Kivy and the native iOS development combo to not meet my needs, Xamarin is the next stop for me.