I know we are talking Heat pump, but be careful how you word this!You should only vent your WH outside if intake and exhaust are both connected to outside
I think the point you are making is, the supply and return airflow both need to go the same place.
This is correct.
If you have the supply venting cooled air into the living space, the living space needs to supply the return air, otherwise airflow issues could compromise the heatpump airflow.