My niece is in a school district that is not urban/inner city. It is decidedly suburban/middle class. It tries to follow the current nutritional standard, but it just fails so miserably in practice. My niece, if she wanted, could have pizza four days a week. Sure, it's "whole wheat" crust, but it's still pizza. Four days a week. And your side for the pizza? "Cheezy bread stix." My SIL is livid. She says one day a week she could get behind. But four?! No. They don't provide anything that doesn't come out of a bag that they can pour directly into a chaffing dish or a box that was frozen.
And my niece is picky when it comes to her lunches. She doesn't like cold cuts and she has decided she doesn't like cheese. And she's in a nut-free room, so she can't bring a peanut butter sandwich. My SIL is at a loss of what to feed Niece that will keep her full and be healthy other than soup, and what child wants to eat soup five days a week?
Niece loves soy sauce. They were going to have her try tofu.
My sympathies to your SIL. Sounds like she's between a rock and a hard place.
They could try homemade (or healthy storebought) chicken fingers for her soy sauce, kebabs are fun for a child (stick on whatever bits of things she will eat), or soybutter instead of peanut butter if the school will allow that.
They are also in a position of not having a lot of money. They pay more in rent to stay in that particular school district (b/c it's so much better than the alternative in our part of town) so the budget gets cut elsewhere. I don't know how much soybutter costs in comparison to peanut butter. Brother is a chef, so I know she eats well at home. The girl loves her salmon ("pink chicken") and I've seen her eat three chicken legs in a sitting. She always has her milk and grapes. It's just tough to keep things hot. I think SIL needs some better quality insulated containers.
My daughter was a lot like your niece - she doesn't like lunchmeat of any kind, would only eat cheese sparingly, and she was also in a nut-free classroom. I sent a lot of hard boiled eggs, greek yogurt with nut-free granola, roasted or fried chicken legs in a heated lunch bag and bagels with flavored cream cheese. She also likes cold shrimp with a mild cocktail sauce, but that is an occasional treat for her.
I've tried a number of them, and I've found that the kid sized thermoses just don't have enough volume to keep food sufficiently warm for the roughly 5 hours it is from packing til lunch. When I want to send her something like soup or spaghetti, I've bought an adult sized thermos and just commit to wasting the excess.