[tpolzer]

Just because 20ms is the default doesn't mean that it has to be that way. The chart you linked shows a big "bubble" for opus for a reason.

Opus minimum frame size is actually 2.5ms: https://tools.ietf.org/html/rfc6716#section-2.1.4

Of course there's a ton of other potential sources of delay that make my fantasy hard to achieve, probably already starting at the typical USB microphones (in headsets/cameras).

[namibj]

20ms rtt through e.g. opus on a loopback network interface is already decidedly non-trivial to archive with "normal" hardware. When you do have low-latency devices, it becomes easy, but not everyone has those.

USB should not really be an issue here, however.