HKG transfer on outbound flight

Of course you can. Assuming that you have mentioned your all stops within the itinerary, your itinerary is definitely eligible for 144 hour visa free transit in wider Shanghai area. Please, note that it is not 144 hour transit visa, but 144 hour visa free transit, so there is no visa of any kind. One more detail... When you have exited mainland China it really does not matter if you will exit or not in Hong Kong because Hong Kong is acts as a third country for visa free transit purposes and the mainland Chinese authorities really do not care what will happen with the rest of your itinerary when you have departed from Shanghai.