Going to Hawaii

You're fine. Hawaii is part of the US. The only thing you have to worry about is if you are going on a cruise. They have their own "towers" when you are out to see and they have high rates. Normally just turn off your phone when on a cruise. 

*Oahu Resident*

I've been to the big island and Oahu, was going to Maui for our anniversary but covid happened and we had to cancel.

Been to all the big 4.  As @gramps28 stated - Hawaii is an American state, and typically has decent service.  I'm assuming that you're flying.  If you're on a cruise to Hawaii… that's a different story.