I'm sure state actors can hack a breadth of devices to achieve such a goal, was just meaning to point out that while cyberattacks tend to be highly scalable, there's enough variation across devices like this that you still need to be moderately lucky and put in some serious work hours to be able to pull this off. It's definitely not a "they just go an' haxx all devices in der" type deal, and it's needlessly alarmist to claim so.

There's also a number of other imaging techniques they can reach for. You mentioned infrared, but they can even use something like WiFi to image behind a wall. All much more circumstance-agnostic and cheap than having to build and maintain an assortment of exploit chains merely for use on a short-notice for echolocation.

If any group has such capabilities developed, they almost certainly use it much more practically (such as for surveillance). And those exploit chains won't be developed by "MIT scientists" who can certainly find a better way to spend their valuable time.