Notifications will need to be well-thought through and customizable for Users so that they're not too noisy. These are the most critical activity feed objects.
List of notifications
Moderation needed: Some other user submitted a change to one of your Pages, approve or disapprove their edits
Page updated: Since Pages will likely be frequently updated, this will be off by default, but these updates will appear in an activity feed in elsewhere in the app. However, a user can opt-in to update notifications if they're very interested in that Page.
New supporter: User began supporting your Page with $1.20 per month!
Sounds & vibration patterns
Colin C. recommends maybe switching up the sounds just for fun, so it's not always the same sound. Perhaps different sounds could be used for different types of notifications too
Graph showing that Notifications are basically just highly critical activity feed objects.

Source: Document scan Wed Apr 26, 2023 in Apple Notes