I don’t think that’s dumb, and the answer is... sort of. The easiest way to make it work would be to have the device somehow help to heat and cool you internall

I don’t think that’s dumb, and the answer is... sort of. The easiest way to make it work would be to have the device somehow help to heat and cool you internally, which would save you energy. You might be able to use the power to produce ATP or some other metabolic necessity, and deliver it where needed. The problem is that you’d need a respectable amount of radioactive material in you, waaaaay more than you’d need for a pacemaker. It would probably make more sense just to keep some glucose syrup and a hand warmer around.