I’ll ignore the ones I’ve not heard of, but of the ones I’ve heard of:
-
Flutter: Seems quite interesting but it’s very dart-centric, however that means it can generate native code per platform more easily.
-
Haxe: is awesome, one of those language/backends (lot of other things compile ‘to’ haxe as well) that is a secret tool in many arsenals. It’s a bit OOP’ish at times but it’s actually quite well designed and can compile to just about anything (from native machine to C++ to javascript to wasm to so so so many things, I’m not sure of any language that can compile to more things…).
-
React native: Effective at what it does but has too much overhead at times and doesn’t “fit” natively very well on each thing it works on where Haxe and Flutter do much better.
-
Xamarin: .NET cross-compiler essentially, it can take .NET code and compile it for other systems. I’m not a fan of them but more because of their business ethics rather than capabilities. I’ve heard it has a bit of unexpected overhead but not used it so can’t really say how accurate that is.