Running a Turing-complete language in a jail is entirely possible. If you don't give it access to, say, webcam APIs the you can be sure it won't turn the webcam

Running a Turing-complete language in a jail is entirely possible. If you don't give it access to, say, webcam APIs the you can be sure it won't turn the webcam on unless there's a bug in the jail. Of course, proving the jail is secure is awfully difficult but you can at least analyze it at your leisure, and you only have to do it once. I don't know if this is possible as a practical matter but the halting problem doesn't exclude the possibility.