Multi-screen SwiftUI app setup using Scenes

Question

I am trying to set up a SwiftUI app that shows different UI on the device's app and the external, non-interactive display (like Keynote does when presenting).

What I have so far:

• @main app structure with @UIApplicationDelegateAdaptor(AppDelegate.self)
• InternalDisplayView and ExternalDisplayView. If possible I would like the latter to only show up on an external display (and not for example in another window on an iPad).
• I have noticed that observing UIScreen.didConnectNotification works, but it's deprecated and I suppose will be removed since Xcode 16, hence I want to use UIAppDelegate and UIWindowSceneDelegate.

I have tried both setting up the info.plist with two different scene types and setting up none, set Enable Multiple Windows to both YES and NO.

In AppDelegate I have:

    func application(
        _ application: UIApplication,
        configurationForConnecting connectingSceneSession: UISceneSession,
        options: UIScene.ConnectionOptions
    ) -> UISceneConfiguration {
        let config: UISceneConfiguration = if connectingSceneSession.configuration.role == .windowExternalDisplayNonInteractive {
            .init(name: "External", 
                  sessionRole: .windowExternalDisplayNonInteractive)
        } else {
            .init(name: "Default", 
                  sessionRole: connectingSceneSession.role)
        }
        config.delegateClass = SceneDelegate.self // my custom SceneDelegate
        return config
    }

But when connecting an external display the .windowExternalDisplayNonInteractive role is not set. In fact, this AppDelegate function does not get called when display connects at all.

What am I doing incorrectly in this setup?