There are plenty of twitch streams that have latency under 2 seconds in low latency mode. You have to watch the source stream and the streamer can't use larger

There are plenty of twitch streams that have latency under 2 seconds in low latency mode. You have to watch the source stream and the streamer can't use larger buffers, but it has already been done for well over a year or more. If a streamer has the chat window on screen you can type something in and see it on stream in two seconds. I have seen private mixer streams have 2 second latency also.