Another library that I would recommend people look into for live streaming to WebRTC, as an alternative to Pion used in this project, is Janus WebRTC Server. I use it for ingesting RTP streams I generate from usb webcams and then playing it with very low latency in the browser. It even has a feature where you can stream multiple streams simultaneously. It also has a simple http api for adding, updating, and removing streams on demand.
Here is the library's streaming demo:
https://janus.conf.meetecho.com/demos/streaming.html