Yes. It can use either XAML or C# markup. I think it uses the same stuff as Xamarin did when you developed Xamarin Native where you were using C# bindings to the native UI SDKs. The developer experience is a lot better than Xamarin because now they have a single C# project that targets everything--Linux, Windows, Mac, web, Android, and iOS at least.
Uno sits on top of .NET for iOS/Android, aka Xamarin "Classic".
Single Project/Single Codebase with your choice of XAML or C# Markup, choice of Native or Skia-based rendering, works with VS/Code/Rider on Windows/macOS/Linux.
