I thought it was just that it was too difficult to fit all the parts efficiently in such a small box

When Tesla first publicized 3d printing the “octovalve” as a piece to complex to manufacture traditionally, the claim was that it made the heat pump much more compact. There was even a rumor going around that they might use it to enter the home heat pump market. Their work in making heat pumps compact enough for cars could really make a difference, however I image home stuff is much more price sensitive