The FDA has been authorized (and mandated) by Congress to regulate medical devices (including hearing aids, among other things) since the Medical Device Regulat

The FDA has been authorized (and mandated) by Congress to regulate medical devices (including hearing aids, among other things) since the Medical Device Regulation Act was passed in 1976-- this isn't a regulatory agency reaching outside its authorized purview, nor is it the same sort of legal ambiguity that was in question with West Virgina v. EPA. If you want less regulation in this space, that's a change in the law that needs to go through Congress. Which is exactly what happened here for hearing aids.