applesbana So I understand that google play services notifications are not encrypted (unlike iOS). However, it seems some privacy conscious apps like signal limit the information they send in a notification and limit what google gathers.
Are you referring to push notifications with FCM using Google Play Services?
In that case, all Google has access to is the name of the app which has a push notification. The notification itself is delivered encrypted directly from the app's server to the app on your phone.
Other installed apps, including Google Play Services, can't read the contents of notifications for others apps, unless you give that explicit permission to that highly sensitive permission. That's certainly not required for push notifications with Google Play Services.