CatalystSwiftUISidebar
Really trivial example showing how to wrap SwiftUI in a UISplitViewController, so that you can use the correct sidebar background style when building for macOS.
N.B. the built-in SidebarListStyle does not behave correctly on macOS, so if you want to look like a Mac app you'll need to have your own, custom list style, or use some other kind of control to populate your sidebar