A wonderful write-up, thank you very much.

However, it needs to be said that with currently available technologies, there is no need to have a 5 seconds buffer.

Have a look at the amazing work of the OvenMedia team (not affiliated). Using their stack, and using Low-Latency HLS (LLHLS) I have been able to easily reach an end-to-end latency between the camera on site to the end-user viewing it in the browser of <500ms. At 20 MBit/s, and using either SRT or RTMP for stream upload.

I understand that most likely your huge buffers come from you expecting your streamers to be using RTMP over crappy links, and therefore you already need to buffer THEIR data. Twitch really should invest in supporting SRT. It's supported in OBS.

Anyway:

Once you have the stream in your backend, the technology to have sub-second latency live streaming using existing web standards is there.

https://airensoft.gitbook.io/ovenmediaengine/

But all of this being said: What you are doing there is looking amazing, so keep up the good work!