Yes @neptunes, the way to make this happen with AppKit was explained during the session, but I'm curious if the SwiftUI solution exists.
vpukhanov
Users receive reputation points by contributing quality content to the forums.
Posts include post and replies published on the forums.
Post authors can mark replies as Accepted to indicate successful solutions.
Apple Developer Forums admins can mark replies as Apple Recommended to indicate an approved solution
Last seen
User for
From
Ярославль, Ярославская область, Россия
Post
Replies
Boosts
Views
Activity
Sidebar is just a List with the listStyle of SidebarListStyle applied to it, like this:
List {
	/* ... contents of the sidebar ... */
}
.listStyle(SidebarListStyle())
You can use NavigationView to display the sidebar side by side with your app's content:
NavigationView {
	Sidebar()
	MainContent()
}
Sidebar can be customised in any way you like, it's a simple SwiftUI List.
You can wrap your button in a ToolbarItem, and explicitly specify the placement, like this:
.toolbar {
		ToolbarItem(placement: ToolbarItemPlacement.navigationBarTrailing) {
				Button("Add", action: makeSandwich)
		}
}
You can see all of the values of the ToolbarItemPlacement in the documentation. - https://developer.apple.com/documentation/swiftui/toolbaritemplacement
As for .navigationBarItems, I'm pretty sure this modifier is not supported on macOS natively, only if you make a Catalyst app. If you want a cross-platform view, you should rather opt for .toolbar.
No, UIImagePickerController is still the way to go