I created a Service with gcloud Run. Using the Integrations tab of the Service, I can connect to a Firestore db instance. Unfortunately I can’t choose an existing instance, hence I have to create a new one.

How can I make the Service and the Android App share the same Firestore db? I am not able to choose the db used by the Android App, either, as apparently there is no way in gcloud console, nor in firebase console, nor in firebase-firestore library for Android.