You should check out HLS and DASH. If you're already familiar and you're not using them because they don't meet your requirements, then apologies for the foolish recommendation. If not, this could solve your problem.
replyI second that it sounds like HLS/DASH (Adaptive live streaming over HTTP) is what you're looking for, instead of RTP/RTMP.
replyWebRTC being a more open model for real-time streaming, but nowhere near as easy or scalable HTTP-based streaming today.
However we can all also start getting excited about MoQ [1][2].
[1] https://moq.dev/