My understanding is Element for Android uses silent notifications out of the box. From https://github.com/vector-im/element-android/blob/develop/docs/notifications.md#how-does-a-mobile-app-receives-push-notification:

The push gateway is configured to only send (eventId,roomId) in the push payload (for better privacy).

My question is, does this apply to rooms that are not end-to-end encrypted?

Use case: I have a private non-federated Matrix instance that I use to bridge other services (Discord, Signal, IRC, etc). These are connected on my private network so no need for E2E here. However, I would like to ensure when Element sends the push notification for those rooms to my phone, that they’re not sending the messages themselves, but rather just the metadata to gather the message from the home server securely.