My tried and true combo is: sandwich (often made in bulk over the weekend and frozen. With meat, cheese and spread) fruit, poppa (frozen in summer) and a snack box item. Snack box is in the cupboard and is only for lunch box treats. Sultanas, fruit bars, popcorn, sometimes biscuits, tubs of fruit/jelly. Shamefully now that I start work early and DS(18) and DD(16) supervise lunchbox packing 3 mornings a week far more leftover KFC heads to school than I would like. DS works there and brings home loads.
Whatever, it's chicken, it's protein and at least they pack it with an ice pack right?