We basically have to options:
- Auth with a key used by the Push Server itself. Everybody would have to white list that key to download their own DMs.
- Change the relay spec to allow a REQ, authed in the past by the user, like on https://github.com/nostr-protocol/nips/pull/1148/
Or maybe DM relays should have their own Push system and each user must set it up in a way that it sends to their NTFY handler when they receive a new one.
Not as easy as Google Play notifications, but it can work.
NTFY has been great and I think the community as a whole should adopt it more heavily
