I assume every service worker is constantly polling a server back-end, or, at least, has a long-running connection?

There are hundreds of service workers installed for me in Chrome (see: chrome://serviceworker-internals/)

I recall on iOS, Apple's infrastructure aggregates push notifications on the server-side, meaning an iPhone only has to maintain a connection to a single server for all push notifications.

Are there any similar initiatives for the Push API? Or is it simply not a priority, given the looser bandwidth/CPU constraints on desktop computers?