Yes, airdrops are only done with permission from Israel since they control Gaza airspace (they have for decades). But airdrops are not an efficient way to feed millions of people (and the pallets have killed multiple people by landing on them). Shipping by truck allows a much larger volume much faster, and the UN has experience doing so, but they have been largely blocked from doing so for months by Israel, which runs its own much less efficient aid operation with many fewer distribution points guarded by mercenaries who regularly kill aid seekers who often have to travel long distances through dangerous areas.