Recent reporting from AP indicates that the Israeli blockade has meant that the primary source of explosives used in Hamas missiles are those extracted from unexploded Israeli munitions fired on Gaza.
Iran is mostly only capable of supporting Hamas through intelligence and through designs/blueprints (things that don't really require transport).
Netanyahu is entering the "find out" part of his plan of "fuck around and find out." Maybe having a music festival minutes away from a genocide wasn't the best idea?