I've been looking around, and found this open source program to deal with audio and video calls.
https://peerjs.com/
Games have had voice chat for a very long time, so it's pretty incredible that Construct hasn't even touched on it, despite it being a requested feature for many years now.
Unfortunately, I do not know real coding, so have no idea how to do something like this... but if someone were to develop a plugin, I'd happily pay for it.