Not easy probably, but likely doable, when someone think it is worth the effort. When the goal is security, because you feel (rightfully or not) targeted by state level intelligence, false sense of security can be dangerous:
It was just a random link. There are plenty of other articles in that area I read about, because I do care about privacy. I do not have them at hand - but the point stands - it is possible. So if there are speakers connected - I assume someone could listen.
Maybe not at all likely (in my case) but when we talk about real security and for some people this is indeed a question of live and death, then I don't want to promote half solutions.
edit: to clarify.
, yes a microphone killswitch is probabyl useful in the way that it eliminates most common attack vectors to silently listening to people, but it is potential harmful if people would rely on it for 100% - but do get listened to and send to gulag because the local KGB did in fact took the effort to implement such spyware
https://www.hackread.com/hackers-steal-data-air-gapped-pcs-m...