I just spent a few weeks playing with the new Breadcrumb Bluetooth Trackable Nocks. They are designed to not aid recovery of the deer, but of the arrow. Finding the arrow is critical to help decide how much time the deer needs left before taking up the trail. Often times, I have struggled to find my lighted nocks after passing through a deer. The either bury under the leaf litter or skip away to parts unknown. The other advantage is the cost these days of arrow set ups. Some of the set ups I am shooting are around $40-50 an arrow. I don't like the thought of leaving one in the woods.
The Breadcrumb nock can be controlled by the user through their phone. You can home in on it, make it flash, or even make an audible beeping sequence to help find it.
With all of that said, they are illegal in Pa.
I support all hunters, regardless of weapon or technique!