This made me think of The Thing, a fascinating listening device made by the Soviets that was completely passive until powered remotely. Very difficult to detect when unpowered.
The Eye of Sauron paper does acknowledge the limitations that would likely prevent it from working against such a device. Impressive nonetheless. True privacy/security is just very hard!
https://en.wikipedia.org/wiki/The_Thing_(listening_device)
And then I thought, something similar might be possible for video. Turns out, yep.
https://ieeexplore.ieee.org/document/8719264
The Eye of Sauron paper does acknowledge the limitations that would likely prevent it from working against such a device. Impressive nonetheless. True privacy/security is just very hard!