Godot?

Targets Windows, UWP, MacOS, Linux, BSD, Android, iOS, and Web: https://docs.godotengine.org/en/stable/about/faq.html

Nothing says you have to use it to make a game. I recall seeing articles here on HN about using it as a cross-platform app development framework. GDScript may be less appealing than JavaScript, however.

Godot is wonderful. But GDScript is a horrible, terrible, ill conceived idea.

So how's the QuakeC development ecosystem these days? How good is ChatGPT at generating QuakeC?

Who's still programming Unity3D in Managed JScript or Boo?

I wonder if Bevy might be a good alternative, it's in Rust which isn't a proprietary language.

How’s accessibility and access to native apis?

Flutter works pretty well for apps like these.