Document-based SwiftData App Playgrounds

Is it possible to create SwiftData Document-based apps in App Playgrounds (or Swift Packages, since App Playgrounds are a special type of packages)?

As explained in wwdc2023-10154, to create a document-based app you are required to provide an UTType that conforms to com.apple.package. This requires your file type to be declared and exported in the Info.plist file of an Xcode project, but App Playgrounds don't have them.

Providing .package as a UTType seems to partially work:

import SwiftUI
import SwiftData

@main
struct SwiftDataFlashCardSample: App {
    var body: some Scene {
        #if os(iOS) || os(macOS)
        DocumentGroup(editing: Card.self, contentType: .package) {
            ContentView()
        }
        #else
        WindowGroup {
            ContentView()
        }
        .modelContainer(for: Card.self)
        #endif
    }
}

This way I am able to run the app, create and edit new document, and save it on disk. However, opening it again does not work (you cannot select it since it is a folder without a defined package type).

Is there any workaround to this?

I guess I could drop support for multiple documents entirely if this is not possible (I don't think this would affect my submission), but I would just like to check if there is any way to do this first.