I am not a database developer but, from the very little knowledge I have and the kind of projects I have worked on (an android application, something similar to your idea, where store owners create their own store and users rate, comment (using custom generated forms) and upload pictures on these stores, github link: github.com/shivani26shinde/Projects/tree/master/F…) where, I have used Firebase Storage (not Firebase Realtime DB) to upload pictures and MySQL for the complex querying (like storing user details, store details, form details), I would suggest you to study and research, a little more on Firebase Realtime DB because, if it is able to do the task just like any other database, it will be the best choice.
The only reason why, I didn't prefer to use Firebase Realtime DB is, less support for complex querying (and this application was created almost 7 months back so, lack of Firebase DB knowledge but, today it might be totally different and convenient).
Again, as I am not proficient with databases and have very little information, I couldn't suggest any concrete solution or answer to your question. But, I hope the link mentioned above, helps you (in some way) finding an answer to your question.