Thank you for the list. To be able to see other parents list for their children is reassuring.
I would maybe add a steel cup that could fit under the water bottle.
Belt (attach flashlight / water bottle)
Small bottle with Coconut oil to prevent sunburn. Can also be used in cooking.
Small map of area. Some contact details of relatives. Money
Teach your child how to open can food. A small compass (attached to the zipper) also keeps them busy.