Is it possible to use SwiftUI in Storyboards on Apple Watch using WKHostingController like on iOS?
Is it possible to use SwiftUI in Storyboards on Apple Watch?
Have a look here.
If I understand your question, that's what you are looking for:
https://developer.apple.com/tutorials/swiftui/creating-a-watchos-app
You do not use storyboard (because SwiftUI you define UI programmatically), but preview gives you most of what you do with Watch "storyboards"