That's not a new sense, just using the existing tactile system with a magnet.

Senses are defined by what they sense, not how they are sensed. A person can have their sight partially restored through implants that bypass rod/cone activation. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6934168/

That's still signaling through the optic nerve.

If they would restore vision by using e.g. the cochlear nerve, that would be something.

you'd be surprised.

I've heard about people experimenting by wearing a belt with dozens of haptic motors and a compass, so that it always indicates the direction of north. After a while wearing it, they stop consciously feeling the sensation of the vibration, and just feel "northness". And then when they take off the belt, they feel weirdly disoriented for a while, even in familiar places.