airplay-sonos | AirPlay server for Sonos devices | Audio Utils library

I'm integrating the Sonos Control API into an iOS app. In our app:

• the user is signed in either to Apple Music or Spotify via an Apple Music subscription or a Spotify premium account.
• the user can play Apple Music and Spotify content within our app (we have the track / album IDs and use this to play music via the Spotiy / Apple Music APIs).
• the user also has the Sonos app installed, and is logged in to their music service of choice (Spotify or Apple Music).

Now when the user is listening to a track in our app, we'd like the user to be able to listen to it via their Sonos device. Our app is for children and has parental control, so the user needs to stay within in our app.

Is there currently any way to achieve this?

Options we've looked into:

1. Streaming: As I understand it, there is no way to stream audio to a Sonos device. The AirPlay-Sonos compatibility is not an option as we're targeting all Sonos devices.

2. Sonos Control API: We then looked into starting the track using the Spotify or Apple Music track ID via the Sonos Control API, but this answer seems to imply that this is not possible. Is this true even if the user is logged in to the Spotify / Apple Music service both in our app and in the Sonos app? For example I could imagine using createSession with a Spotify / Apple Music accountID so that I would have access to these services, and then using loadCloudQueue to load the trackIDs. But I could be misunderstanding the API.

3. sonos-objc: This looked promising, but is very outdated and we haven't managed to set it up.

Any leads on this would be greatly appreciated.

Thanks!