This is ethical despite it walking the line of taboo. It hurts no one, and if the tissue sample can be extracted at home without causing damage to the donor I see no issue with it.
Sure, but where's the upside? (ethically, not sure if consuming your own meat could have some sort of weird effect on you, even though afaik the usual cannibalism issues wouldn't apply). If anything it's more ethical to take it from yourself because you consent to it, the farm animal probably doesn't.