Does Apple have good channels for conbating app-originated spam? Can intercepting proxies in the form of a VPN do some sort of filtering of incoming APNS notifications? Is there something else that I’m missing?
"Apple Push Notification service is a platform notification service created by Apple Inc. that enables third party application developers to send notification data to applications installed on Apple devices. The notification information sent can include badges, sounds, newsstand updates, or custom text alerts."
So, notifications.
If an app annoys me with notifications then I disable the app’s notifications.
Try using the web version of some apps when possible.