I've kept my eyes open for such things, as barakta has a severe conductive hearing loss that is effectively bypassed by bone conduction, and headphones are likely to be cheaper and more rugged than her
BAHAs.
There's very little out there, and what there is tends to sit in front of the ear, supported by the pinna, so isn't suitable for her.
With bone conduction there's always going to be a severe trade-off of transducer head-clamping-force
[1] against frequency response, and as the skull is a single bone, stereo channel separation is poor. Fine for speech, but hardly hi-fi. The main advantage is that they don't obstruct your normal hearing (or require a functional middle ear). The sound from the transducers is likely to be audible to those nearby, in line with that from conventional open-back earphones.
[1] If you wear one for enough hours a day, having a hole drilled in your skull starts to be an attractive option.