Well, Uno (AvaloniaUI's competitor) uses WinUI 3 as a back-end on Windows. And NAOT-compiled Avalonia on Windows is practically native anyway. You can use both

Well, Uno (AvaloniaUI's competitor) uses WinUI 3 as a back-end on Windows. And NAOT-compiled Avalonia on Windows is practically native anyway. You can use both to build against macOS too if you want to target both major OSes. The offerings have improved significantly over the years. But yes, I get your point, if you're not familiar with C# (or Dart or Kotlin for that matter), there is motly a one way out in the form of a web app.