A difficult thing to do in some countries is to eat/drink locally as a sustainable means of travel.
In Hawaii, the only drink that I could find readily available that was made in Hawaii (not from mainland or anywhere else in the world) was POG. A canned juice drink that costs about 0.79c at an ABC store. Cheaper than most other beverages.
There is a Foodland at Ala Moana Shopping Centre, but not too many grocery stores in Waikiki itself. Most food at the grocery store also is from the mainland.
At the Ala Moana Shopping Centre food court, near one of the bus terminals, the following places were good:
Poi Bowl – serves purely Hawaiian local food. A tray of the local specialties is $9.69
Not all Hawaiian food may be to your taste. There’s definitely a seafood and asian influence in the food. The pork was delicious. The food was very similar to a the that which was served at a Luau in the Waikiki aquarium.
Chinatown Express – make decent hot Chinese buns.
Mahaloha burgers in the food court, on the second floor of the
Royal Hawaiian Shopping Center, make decent locally sourced burgers.