New NavigationSplitView is hard to use on watchOS.
NavigationSplitView requires List to selection (for NavigationLink's init(_:value:)
),
but all selection methods are marked as unavailable on watchOS.
(https://developer.apple.com/documentation/swiftui/navigationsplitview)
(https://developer.apple.com/documentation/swiftui/list/init(_:selection:rowcontent:)-1q8lq)
Well, It can be use old deprecated init(_:destination:)
on NavigationLink... but It is weird.
I filled feedback. (FB11403019)