[keep_reading]

Pushover.net does it just fine.

https://support.pushover.net/i46-are-messages-notifications-...

My understanding is that Pushover encrypts the message with your device's public key (from the app) and delivers it through Apple/Google. On iOS you need a special permission from Apple to "filter" push notifications and this is the hook they use to capture and decrypt it before displaying it on your phone

[graphe]

Can it hide or obscure the metadata at the time sent and received? Signal says they do that for their chats but you can also download an archive.

[keep_reading]

I don't know, but I would assume not.