public static class ARWorldMapSender
{
    public static void SendARWorld()
    {
        var mcSession = UnityMCSessionNativeInterface.GetMcSessionNativeInterface();
        var arSession = UnityARSessionNativeInterface.GetARSessionNativeInterface();

        arSession.GetCurrentWorldMapAsync(worldMap => {
            mcSession.SendToAllPeers(worldMap.SerializeToByteArray());
        });
    }
}

public class ARWorldMapReceiver : MonoBehaviour
{
    [SerializeField] UnityARCameraManager arCameraManager;

    void Start()
    {
        UnityMCSessionNativeInterface.GetMcSessionNativeInterface().DataReceivedEvent += OnDataReceived;
    }

    void OnDataReceived(byte[] data)
    {
        var worldMap = ARWorldMap.SerializeFromByteArray(data);
        UnityARSessionNativeInterface.ARSessionShouldAttemptRelocalization = true;
        var config = arCameraManager.sessionConfiguration;
        config.worldMap = worldMap;
        UnityARSessionRunOption runOption =
            UnityARSessionRunOption.ARSessionRunOptionRemoveExistingAnchors |
            UnityARSessionRunOption.ARSessionRunOptionResetTracking;
        UnityARSessionNativeInterface.GetARSessionNativeInterface()
            .RunWithConfigAndOptions(config, runOption);
    }
}