I think we talked about this before with regard to a tooth magnet and bone conduction… you gotta keep the dead weight (non-magnetic mass) down as much as possible. A fingernail will drastically blunt the sensation. If you could get an N52 strength magnet and use a drop of glue that was only as wide in diameter as the magnet itself (no extra mass or fulcrum style leverage working against it), I think gluing a magnet to your much more sensitive finger pad would give you a more accurate idea of what you might be able to experience with a magnet implant. It would be extremely temporary of course, but if you set up some experiments ahead of time, you would only need a few good working minutes to get the gist.
In short, big blobs of glue will probably result in lower resolution… meaning low frequency magnetic field changes will still be easily felt but higher frequency stuff might not… maybe 60hz from the microwave will be within the “low range” spectrum of sensation… and of course just boosting the power could also result in some sensation as well… though maybe not really equivalent as to what you’d feel as an implant.
Anyway I think if you have enough magnets, you could make an experiment out of it and glue some to the finger pads on one hand and some to the nails on the other and see which are more sensitive!