I checked it out a while back. It still requires you to write two different UIs in two different frameworks: SwiftUI or Appkit on Mac, and WinUI on Windows. It's just that now you can write WinUI code in Swift instead of C#.

I mean I guess that makes sense as it’d be a pretty big project to port Appkit to windows APIs, but that’s not really a great benefit in terms of cross-platform development. I guess if you’re building something like a browser, you’re going so low level anyways that most of those cross-platform bells and whistles don’t provide much benefit.