> ...build whichever kind of audio/video applications...

Is live streaming a use-case that's under scope? If so, can the client P2P or requires a relay server for all traffic?

Well, it's webRTC. So the main use case is live video streaming. But one would need to define 'live'. webRTC is really made for sub-second latency, which you need for conversations. If you don't require this you're better of using HLS streaming. Because achieving ultra-low latency does come with tradeoffs in complexity and quality.

webRTC is peer 2 peer, but that doesn't work if you have a lot of peers. That is where an SFU like mediasoup comes into the picture. That's a kind of relay server so you can send to many peers still over webRTC (thus with ultra low latency). Also, if the peers are behind firewalls, peer 2 peer also doesn't work and you need a TURN server to relay the video.

PornHub uses mediasoup for live cams.

That’s quite the endorsement.

exactly what I was thinking :)

I think there's nothing stopping you from attempting that, but you would need some pretty complex client software to get a good experience with P2P live streaming.