They can, and they do: https://www.theguardian.com/world/2023/oct/19/egypt-rafah-crossing-aid-enter-gaza-why-closed-israel-us-egypt?trk=public_post_comment-text

Dont quote me on this, but i think the majority (all) of aid comes through egypt.

Thing is, it "has" to have the supervision of Israel or else they would whine about weapons in trucks.