The OUI scanning approach is correct but has a hard ceiling: it only works while the device is actively transmitting. Offline recording mode — which Meta Ray-Bans support — breaks detection entirely. Same limitation applies to the ESP32/FLOCK detector you linked: passive RF emission detection fails against any motivated actor who knows the countermeasure exists. Airplane mode, or a device with no wireless stack at all, makes both invisible. The app is useful for ambient deterrence — most casual wearers won’t bother — but it’s not adversarial detection. The threat model it actually solves is ‘oblivious person wearing Ray-Bans in a coffee shop,’ not ‘person deliberately surveilling you.’