I struggled with this. We implemented Firestore (successfully) in a production mobile game for the real-time chat and configuration aspects. The SDK WebSocket i

I struggled with this. We implemented Firestore (successfully) in a production mobile game for the real-time chat and configuration aspects. The SDK WebSocket implementation for real-time updates was a huge factor here. At the time we were using the Firestore beta, Security Rules were also very poorly documented with no tooling apart from the editor (beta product - I know, I know). Ultimately we found several vulnerabilities in our own implementation of Firestore that were difficult or practically impossible to resolve on our end. The workaround was to communicate with Firestore only by using the admin SDK. I still completely vouch for Firestore and Firebase as a product.