Conceptually feasible, the biggest risk I see is I can’t say I have ever seen an inductive coil that is 3 dimensionally curved. The way inductive charging works I’m not sure if that shape would result in the magnetic field being directed all over the place. But I’m willing to believe it could be done, even if it involved flattening the mating surface.
With that said, if the design was more important than the wireless charging, you could easily achieve this with an Airpod-like approach where there were two small metal contacts on the outside of the headphone and your magnetic loop simply held the charge contacts in place.