How should I build this app over communcation apps?

These days I am finding myself in the position of having to implement for one of my college courses a system that should act as a giant wrapper over many communications apps like Gmail , Facebook Messenger maybe even WhatsApp .To put it simply you should have a giant web interface where you can authorize Gmail , Messenger and use them at once when required. I am thinking of going with an REST API to manage the user's services authorized by OAuth2.Also I am thinking of using Node.JS and Express.js in the backend and React.js in the frontend. I found some sweet libraries in npm that should take care of interacting with the involved APIs(https://www.npmjs.com/package/node-gmail-api this one for instance), but I am also doubtful about this approach , for example I have no idea how to keep the use notified about its incoming mails or messages for example . I am in dire need of some expertise since I forgot to mention but I am quite the newbie in this field. To sum it up for once my question is how would you implement such an infrastructure ? Is it my approach viable or I am bound to hit some really hard to overcome obstacles?