Which database is suitable for Python Flask?
Learn Flask: https://gumroad.com/l/IMzBy
Flask is a micro framework, this means you can develop your app but you're not forced into a certain architecture like django does.
So you can use any database system or even an object relational manager, but you don't have to. You are free to create your own app design, you can even chose not to use a database at all.
You can add any Python modules to your Python Flask web app!