I just learned about this today, and this (from the FAQ) helped me understand how to think about it:
"Avalonia is akin to Flutter for .NET, both using Skia for UI rendering. Key differences include Avalonia's use of .NET and XAML, contrasting with Flutter's Dart language. While Flutter excels in mobile, Avalonia has recently expanded to mobile, offering a more mature desktop experience. For teams skilled in .NET and XAML, Avalonia is likely the better fit."
So this might be a great choice if you're a .NET shop, if your app doesn't need a platform-native native look or feel, and if your project is desktop-focused.
"Avalonia is akin to Flutter for .NET, both using Skia for UI rendering. Key differences include Avalonia's use of .NET and XAML, contrasting with Flutter's Dart language. While Flutter excels in mobile, Avalonia has recently expanded to mobile, offering a more mature desktop experience. For teams skilled in .NET and XAML, Avalonia is likely the better fit."
So this might be a great choice if you're a .NET shop, if your app doesn't need a platform-native native look or feel, and if your project is desktop-focused.