Safari Push Notifications documentation deprecated?

That documentation is old, but it is the only piece of documentation available for Safari Push Notifications.

The documentation is mostly accurate, except for the Pushing Notifications section, which references the now shut down binary interface for sending pushes. Instead, you would use the HTTP/2 based interface described here: https://developer.apple.com/documentation/usernotifications/setting_up_a_remote_notification_server/sending_notification_requests_to_apns/

More information about the HTTP/2 provider API can be found in these two WWDC sessions:
WWDC2015 Whats New in Notifications <https://developer.apple.com/videos/play/wwdc2015/720/>
WWDC2016 Whats New in the Apple Push Notification Service <https://developer.apple.com/videos/play/wwdc2016/724/>

The rest of the information is still valid, as to how you would create a push package on your server, etc.
Just the section of making a push request has changed.

Safari notifications work on Desktop but still do not work in iOS (June 2021). Please see:

https://developer.apple.com/forums/thread/681748

For a more detailed discussion.