I think primarily the purpose is to expose the hypocrisy of the left.  The wall is a WINNING issue for POTUS with the majority of the public supporting it, across party lines. The shutdown also does something else. It provides a measure of cover for the Q team during operations.  The shutdown keeps about 25%-30% of Government employees home, which likely includes a sizable number of disloyal deep state type people, who now will be out of the loop. Additional neutralization of deep state comms is especially useful if the Q team is accelerating operations at this time.