Maybe the problem is the size of the implant. I've seen pictures of rice-sized implants - that's IMHO far too big to go into a fingertip - unless you don't use your finger at all.

A smaller implant would be less sensitive to magnetic fields, ie less distracting.

I'm not really into implants, but maybe something no bigger than a needle could be tested by an eager volunteer?

A biocompatible coating is needed, which increases the size - the technical challenge is making an implant small enough, coating included, to be helpful without being painful or distracting