Where do you get that Israel is the 4th largest military power? They're not.
Israel’s military is strong but has been significantly strained by the ongoing war, though it remains fully operational. Missile defence systems such as Iron Dome and Arrow are being used at an intense rate, severely depleting interceptor and ammunition stockpiles. The financial cost is staggering, with estimates suggesting daily war expenses of $725 million—and in some cases, exceeding $3 billion during operations against Iran. The sustained pressure has pushed it to the limits of its manpower and logistical capacity.
Gaza does have an army. It's lead by Hamas who have a military wing. Who very effectively performed a sophisticated invasion of Israel. They're currently hiding because they'd rather everyone else die.
Ome thing you are right about is that Gaza has no airforce, or navy. Thank God otherwise imagine what they'd have done with it.