Just go with what you know works.
It's all very well schools preaching about healthy eating, but many kids just don't like it.
I used to try hard to put variety in lunchboxes, like different fruits and sticks of raw vegetables. My kids asked me not to.
Mine aren't fussy eaters normally, but the problem seemed to be that their primary school gave no priority to those on packed lunches (a fair number of them), and tried to squeeze them all into the last ten minutes of the lunch hour.
I never could work that one out.
People would complain, then it would improve briefly but never permanently.
Glad they are at secondary school now. All much less "in your face", thankfully.