That looks fascinating, I would love to know the physics of that ring and how it works. I had always assumed you needed a whole solid ferrous ring touching the glass plate whereas this is only touching in three places. It must then be electrically conducting from the ring to the Wok to induct the eddy current as those three points wouldn’t be enough to conduct heat.

Alternatively maybe it’s just relying on inducting directly to the Wok bottom but the surface area touching the glass plate is very small so I can’t see it working well.