Yes, electronics is extremely useful for building the widgets involved in open heart surgery. No, electronics and open heart surgery are not fundamentally the same. The technical success of cryonics relates to issues in several areas, including cryobiology, neuroscience, biochemistry, medicine, physics, etc. etc. In the former, a new technical idea is presented in an emotionally loaded context and in a framework which almost begs to be rejected. In the latter, people can become familiar with a new technical concept in an emotionally neutral or positive framework.
Nanotechnology discusses ways of arranging atoms.
As such, it is simply the logical extension of work in physics, chemistry, biochemistry, scanning tunnelling microscopy, etc. The gut response will then be to view both with great suspicion. Still, most people will be familiar with neither nanotechnology nor cryonics, and so will react emotionally and reject both. Everyone knows that medical technology is good, and future medical technology must be even better. Cryonics is unfamiliar, but at least we've got some familiar words and ideas in the title.