Whenever I subscribe to a collection of documents, I'm able to extract the changes to the documents, given that the listener returns DocumentChange. This way I can understand whether a given doc was created, modified or deleted.
How to get the DocumentChange when subscribing to a single document in the collection? The issue appears to be that this time the listener returns DocumentSnapshot instead of DocumentChange.

Firestore subscribed document change type
The DocumentSnapshot contains everything you need to know about that one document.  Either it exists() with data, or it does not.  You can check this state with each new snapshot for that one document, and react to that any way you like.  Since you are not performing a query with variable set of results, there is no need for more information.
