It really depends on the type of application. A Drawing application, where the 'core' is the drawing/filter/etc code, should probably be done in a shared libra

It really depends on the type of application. A Drawing application, where the 'core' is the drawing/filter/etc code, should probably be done in a shared library (C/C++/Rust?) and then have a native UI as the UI won't be the complicated thing. A Video editing app (where the UI for timelines, etc etc) where the UI is quite important, should probably be a mix where generic stuff (menus, buttons) use the native libs, but then have most of their controls rendered independently of the native UI lib (timeline, custom controls, etc). A audio mixer where the UI is mostly all custom, you can even do it in Unity (or Gogot/OpenGL/whatever) as 95% of it will be custom. A 'show data' ui filled with tables and lists and the likes, while I don't like, probably something like Electron would work. Or QT/wxWidgets A game pretty much doesn't matter and use a game engine that is supported in all platforms. I would recommend to use something like QT/wxWidgets/Xamarin Forms/etc as a generic take all, and depending on the app, adapt it to your needs.