Most efficient way to story multiple similar items in nosql database

I have multiple objects that represent the same general type of item and will be grouped into a single collection client side. However, I am trying to find and understand an efficient way to store these objects in Firebase Firestore.

My initial thought is to create a single collection and persist each object type in that collection and when I map my remote object to my cache object I will add a flag which will determine what object I need to cast it to when I map my cache object to my domain object.