Not sure how I feel about it. If they had a pair of hiking boots with it built in while your walking and swinging fields or woods that might be interesting. If it actually worked right could give you an advantage . If anything it’s more novelty and for a beginner I feel.
This crossed my mind once while walking on a tour around a historic site. I thought to myself gosh I’d love to know whats in the ground here! And the wheels started turning. I’m sure I’m not the only one. Not that you’d attempt any sort of recovery.. just listening to the signals for pleasure!
A better idea would be to simply strap detector coils to the stomachs of wild coyotes and release them into whatever area you plan to search. Then whenever the detectors hit on something they automatically record the location to GPS which is uploaded wirelessly to your smartphone. Then you simply follow up on each signal one at a time, the coyotes constantly adding more and more targets for as long as the lithium battery packs tied to their backs stay charged.