Well I've not had dinner at Ohana (only breakfast) -but I've read others' posts that their kids were offered basically what was on the kid's menus at Capt'n Cooks and/or Kona.
When we dined at Ohana with my very picky 4 year old she was served chicken nuggets & fries at no additional cost. Don't be afraid to ask for what you want it may very well be available.