I would not donate to Red Cross. They have a history of fundraising using current disasters, but not using the money for that.It looks like Lahaina divers is almost certianly a loss.
From the satellite photos I think the Lahaina location of Maui diving is also at a minimum extensively damaged if not also completely destroyed.
Aside from the donations to the Red Cross and salvation army, if any of the local dive shops happen to have kept product offsite (hats, shirts, etc) once they get their feet under them I’d absolutely buy some. It isn’t much, but looking to help any way I can.