Sending push notifications to iOS without relying on a native app has already become a mature option. Last year Apple extended the standard Web Push with Declarative Web Push, which finally makes the whole thing make sense. (It's handled natively by WebKit rather than driven by JavaScript, which improves push reliability and privacy, much like the native push notification model.)

Kukuroo uses Cloudflare Workers so that end devices can subscribe to push notifications and relay push requests to the Worker, which signs and delivers them. I personally found it genuinely useful and full of potential, so I open sourced it: kukuroo.cc

Requirements:

Safari on iOS and macOS only (though seriously, who receives push notifications on macOS?) The web page that receives the notifications has to be added to the Home Screen A Cloudflare account. Push notifications and lightweight serverless functions are a perfect match

It sounds like adding a Safari web app to your home screen is a slightly janky delivery mechanism?

Could you use Safari for delivering the notifications even if your default browser is something else?

Are there any solutions to encrypting notifications so that the service provider cannot see them?

I use FCNS or APNS to send notifications to mobile apps, its a bit of hassle but it reaches all platforms.

It'd be great if this solution reaches all browsers on all OS but I can see the potential for spamming , might be why Apple and Android require photo id now.

Seems nice! I use FCM (Firebase) which does this for Android and iOS, which does require some setup, but it's not too bad