> For example, if you have a MusicKit Song, you could pass song.id.rawValue as the productID parameter to the MPMediaPlaylist's addItem(withProductID: ) This would be great to explicitly state in the docs - I wasn't clear on this point and was very confused about how to integrate MusicKit and the Media Player API until I stumbled across this comment.

Even if you can't support MusicKit in the simulator, could you provide a way to get "artificial" data? Placeholder albums, or something? As it is I'm having to write a shim layer between MusicKit and the rest of my app, because otherwise unit testing and SwiftUI previews are just impossible.