Thank you for your response.
I disagree that the scope of this question is too wide, further, the educational value of the answer would outweigh the effort required to produce it.
You would need screenshots of Firestore collections and data, plus screenshots of the Firestore security rules. You would also need screenshots of the UI code, for example the queries producing results that are displayed. Together these would help to make a reproducible example.
Are you certain that the get(/databases/) function actually works? It seems that there is no proof, and the logic you have used to explain the function doesn't add up, does it?