What is the entry point for creating a streaming app?

Question

Video broadcast

Please tell me the entry point for creating an analogue of Twitch / any other video streaming service (for learning purposes). Interested in exactly the technologies and tools that will come in handy, and how to google everything. (has knowledge of ubuntu, nginx a bit, php, golang). I would like to start at least with something elementary - so that I can start the broadcast through OBS, and view it via the link in the browser. But I don't know how to step up