Web notifications don’t work on iOS and I’m assuming Android as well? Serviceworkers aren’t woken up in response to a background push if your phone is lock and not on that webpage.
From a user standpoint, Web Notifications work quite well on Android. When using Chrome for Android (Chromium), each site is assigned a separate Notification Channel so users can change notification priority or block notifications. Firefox for Android (Gecko) works similarly but without Notification Channels.
Web notifications work fine on Android. Has Apple still not fixed notifications then? I was under the impression that they claimed to have massively improve Safari during last year's conference?