Is it possible to record video call session in Android app?

We want to develop a video call app between web and android clients. It is required to record at least the android peer’s video & audio during the call session with resolution at least 720p. How can I do this? Is there a guide/tutorial?

Yes, you can record the all streams in the media session:

https://openvidu.io/docs/advanced-features/recording/

The recording takes place on server or on client?

As you can see in the docs, recordings are saved in the server.