Firebase with existing Express backend suggestions

Hello everyone. This is not really an ionic specific problem, but because I am using ionic on the client, I am posting it here. I am working on an Ionic 2 app that allows users to create choices and vote on choices. For this REST functionality I use express and a mysql database. However, next to this REST functionality I would also like to add a timeline (or live feed) to the app that shows ‘somewhat’ real time new choices created by friends and in the future also actions that a friend has taken (voting, liking for example). Because I already created the express backend, I am thinking about using firebase for the real-time feed and perhaps social authentication of the user. Would this be an appropriate approach or should I add websockets (using to the express backend to deal with the live feed? Another way would be to rewrite the backend to use only firebase. Any help would be greatly appreciated.