I would like to build a medium to large scale app, that has real-time operations and a good authentication system and a secure and fast API. Should I use Django with React only? Or maybe use Django for the API, Node.js for real-time operations and React for the frontend? Any suggestions? Which database should I use with those technologies? Should I use both MySQL / PostgreSQL and MongoDB together? Should I use only MongoDB or MySQL / PostgreSQL? Or is it better to go with both MySQL and PostgreSQL at the same time? Should I use also GraphQL?