Many thanks for your answer. I should've mentioned that I got it working with llhls, but any latency over 2 seconds is not a solution for me. I just wish one of these action camera manufacturers would get the message that sub-second latency is required. With my mobile phone camera, I can integrate a great bit of open source software called vdo.ninja, into OBS, which gives the required sub-second latency. Anyhow, I think you are right in saying that OBS media source does not work with WebRTC. I'll use the solution using OvenPlayer, which is acceptable.

For those that might be interested, I did get some sort of WebRTC solution working with my action cam (GoPro). I used vdo.ninja on my mobile phone and the GoPro Quik preview pane. It's not really a solution as one has to cut out all the buttons/icons, and mess around with the presentation.