Caveats
UIScreen Not accessible
This won't be accessible in xrOS because there are no bounds to calculate.
You can just isolate this logic with wildcard checks specifically to avoid VisionOS.
#if !os(xrOS)
#if !os(visionOS)
#endif
Updated from xrOS to visionOS
Updated swift docs
.frame(width: UIScreen.main.bounds.width, height: 200)
It was recommended to use UIWindowScene but I couldn't figure it out.
Previews have different syntax for VisionOS vs iPad / iOS
#Preview {
    ContentView()
}
#Preview(windowStyle: .automatic) {
  MainView()
}