The kind folks over at Apple helped me figure this out. The key bit of information here is: SwiftUI is inherently scene based.

To get the parameters at launch you need to have a Scene Delegate:

class SceneDelegate: NSObject, UIWindowSceneDelegate {
    func scene(_ scene: UIScene, willConnectTo session: UISceneSession, options connectionOptions: UIScene.ConnectionOptions) {
       // Use connectionsOptions
    }
    
    func scene(_ scene: UIScene, openURLContexts URLContexts: Set<UIOpenURLContext>) {
        // Use URLContexts
    }
}