using navigator.sendBeacon() for syncronous realtime unsubscribe and untrack. navigator.sendBeacon()

[PaperPrototype]

I have a use case where it would make sense to do the following:

window.onbeforeunload = () => {
  channel?.untrack();
  channel?.unsubscribe();
};

unfortunately there is no way to reliably send data in onbeforeunload with syncronous methods.