[WorldMaker]

MAUI in .NET 7 checks many of the boxes you have here:

- Native looking: MAUI supports native controls as much as possible

- Cross platform: Nearly everything but Linux today (and there are forks out there trying to bridge that gap); macOS (Catalyst), Windows, iOS, and Android

- C# as the default .NET option is a very sane language. Other options may be possible with more effort. (Some people are still working on that.)

- MAUI's focus is still on declarative XAML UI with databinding (MVVM), but there's a growing community for MVU (vaguely Elm-like) architecture including some official out-of-the-box support now.

[zerr]

It doesn't support the second most popular OS (Win7) which still holds the quarter of the market share.

[WorldMaker]

If you find yourself needing to support an OS that ended security support in Jan 2020, you can easily share 95%+ of your C# business logic between MAUI and a WPF app.