When creating the data model for your apps, do future you a favor and starting tracking metadata like:
createdDate, createdBy, lastUpdatedDate, lastUpdatedBy, firstLogin, appDownloaded, lastOpened, etc.
These can be in a fancy way or just as a prop on your tables.
Good for users, events, posts, messages, and etc.
You can easily put together some code to look at various KPIs/metrics as you get user engagement.