WBOC (Tom Lehman) reports that the new rule provides,

Firearms dealers may conduct sales of firearms, ammunition, and other goods directly related to responsible firearm storage and maintenance, by appointment only. No more than two appointments per half hour shall occur, and sellers are limited to operating during normal working hours they operated on prior to the State of Emergency. Any seller who violates such directive may be subject to criminal prosecution or other civil enforcement remedies up to and including arrest or the involuntary closure of the business.

Hard for me to see much of a justification for the "normal working hours" rule, which I expect will magnify the delay people will face in waiting for an appointment; but it may well be the political compromise that it took to make this happen.

Note that the Pennsylvania Governor likewise originally included gun stores in the closure order, and then likewise changed course.