Interesting product for deaf dog training?

I hope this is allowed. If not please remove - note, I'm not connected in any way with this product, nor have I seen or tried it, but it looks like it could be useful.

https://tractive.com/shop/en/pet-wea...1f4dd-94917801

I'm not sure how user friendly it would be as it's used via a 'phone, but knowing how many can use 'phones like a second skin, it may be easier for those comfortable with them.

Not sure how good it would be if you can't get the dog to look at you when you use it. If the dog is off lead and away from you and really concentrating on something more interesting then possibly the dog would still ignore you. If your dog is profoundly deaf then a long line is far better and saves you losing your dog if it takes off on a more interesting scent.

I agree in a way, but I was thinking from a command standpoint. At least the small vibration would give something of a command.

Obviously, not the magic pill and would still need training, ie accepting the device, training that vibrate means 'come', and still the all important 'give me your attention' and 'check in', but just another little aid to training that may help