I know Waikiki/Oahu isn't some people's favorite island, but we like it (probably because more of our friends/relatives are from this island) but Oahu probably has the most variety of local eats or even the fancier restaurants.
We also like shopping/browsing at Don Quijote, Mitsuwa -good places to pick up some sushi, bentos, or smaller grocery sizes compared to Costco/Sams. And The Andagi Guy is at the Donqi store on certain/days and times if they want to try the andagi (Okinawan fried donut balls) and the local places like Rainbow, Liliha, Mitsu Ken, Ethel's, and even Zippy's are all ono! The other place that many like is Side Street Inn and there's two locations in Honolulu.
Slip also posted a you tube video of some locals who visit different food places, so that might be good to look at. I'm also going to include a link to a google docs that we used to update with local eats, but it hasn't been updated since 2018 and some of those places closed or closed during covid, so yes we know it's not up to date, so just use it as a reference.
https://docs.google.com/spreadsheets/d/1C0HYgdmZsHuyEJh9B1zk5JJPdWw_DH613aCVXkuwEiY/edit?usp=sharing