Seems to me that the ethics are all about the acquisition of the parts, not the operation itself. Whether a single organ or all of them at once, the ethical issues are pretty much the same.
If this capability really existed (which I doubt) it seems too that the larger promise would be in the case of spinal cord injuries. If you can graft one spinal cord to another, a repair of a damaged one would be small potatoes.
The “ethics” are that they have to engage in rehearsal surgeries on live animals before moving to humans.
They’ve done this in the past. All of the surgeries.