Mobile app needs hierarchical data with offline sync and a backend service that enriches data using a service account; the app must scale and be secure. Which database and IAM role should you use?

Firestore in Native mode is ideal for mobile apps due to its hierarchical data model, real-time synchronization, and robust offline capabilities. It scales automatically and offers strong security rules. The roles/datastore.user role grants the service account read/write access to Firestore, enabling it to enrich data. Cloud SQL is a relational database, less suited for hierarchical data and real-time mobile sync. Bigtable is a wide-column NoSQL database, optimized for analytical workloads, not typical mobile app data. Firestore in Datastore mode lacks the real-time sync and offline features of Native mode. The roles/bigtable.viewer and roles/datastore.viewer roles only provide read access, which is insufficient for data enrichment.