Messenger API, REST + WS or pure WebSocket?

Question

Node.js

The essence of the issue is this, I decided to download the messenger for the sake of interest, several technological issues immediately arose.
One of them is how to build an API?
Is it worth mixing REST for state management (by type, change user data, authorization, get profile data, etc.) and WebSocket for communication, of course.
Or is it worth doing everything on sockets at once?

Answer 1

You can combine, you can not combine. You can generally chat through long-polling

Answer 2

Discord, for example, is mixed.
Most importantly, do not do pure http

Answer 3

Just pure WebSocket with its additional point-to-point traffic encryption inside the WSS pipe. All service traffic (login/logout, states, etc.) is in the same place.
So that you can use messaging both on the web and in any native applications for different operating systems.