This is a Telegram bot 🤖 which notifies you when you sell in app purchases or get reviews via Google Play.

The functionality can be provided by one bot or split between multiple, it doesn't really matter. I'll speak of one bot for simplicity reasons.
The code assumes a "serverless" environment, the bot only reacts to events and persistence is handled by a database. More specificly, it is written for the GCP.
The bot is triggered by messages on Pub/Sub topics. IAP notifications are provided via Googles "Real-time developer notifications", which publish to a Pub/Sub topic. New reviews are polled with the Android Publisher API, the polling is triggered by Pub/Sub messages published by Cloud Scheduler. At this point we're already knee deep in Google products, so Firestore was choosen for persistence.

Maybe I'll write a guide one day, until then you'll have to figure it out by yourself, sorry.