The Bone Fone claimed to provide a music listening experience through bone conduction, which is a thing. How well this worked from this device, I am not sure. There are specialty applications of bone conduction for hearing impaired individuals or noisy industrial environments. It doesn't seem to have set the audiophile world on fire, although there were a few clones of the Bone Fone.
Smartphones dethroned Bone Fones from the music zone, but we shouldn't be too prone to moan or disown the shown Bone Fones.
The ad's $70 price is around $280 in 2026 USD.
They're not exactly uncommon. I saw them in stores a few years ago. It looks like the market is for people that want to maintain situational awareness, for which you can also get earbuds with passthrough that also give you the option to reduce noise.
https://www.tomsguide.com/buying-guide/best-bone-conduction-headphones