Use WebRTC without Google firestore

Hi. I have developed an online classroom application using Agora service on react native and react js. Now I need to write my own Service to make video and audio communication between users. Due to the project’s location, I could not use Google Firestore service.
I need some help to figure out what I should do to implement WebRTC in my project.
Is WebSocket or signal an appropriate technology to implement it?

Late response but yes you could use something WebSocket based.
FeathersJS is a good example of a framework sat on top of NodeJS which has a lot of the bare essentials built in to provide an api via REST and SocketIO.
That would allow you to create a service for the purpose of exchanging Session Descriptions and eventually get calls connected together. Don’t forget you will also want to look at using a TURN server to get around restricted networks and essentially create a more stable service.