@streetlight Dark chocolate
PB crackers (can even use wheat thins or nut thins if he'll eat it for extra protein/cover/energy)
Diy lunchable (crackers, meat, cheese), I like someone else's idea of using a pouch of food as an ice pack, that would likely be fine for this stuff
Turkey sticks, they're kinda like slim jims but not as bad on sodium, saturated fats, etc
Chickpea or lentil puffs (we like hippeas and harvest snaps)
Granola bars - Larabars are good, decently healthy, and simple ingredients or Clif Builders are very high in protein but look like candy bars
You can add chia seeds or nuts to everything (yogurt, smoothies, muffins, etc)
Kodiak has a bunch of good recipes, I saw pizza muffins, waffles, and protein balls as all good options.
I like to make yogurt sandwiches for my son sometimes as a change of pace. You can add fruit, PB, chia seeds, etc.
You can freeze a smoothie and then you can really go crazy on healthy ingredients
Salmon or tuna patties (made the night before).
My 19mo didn't have any issue chewing
these chicken jerky bars so you could probably pack something similar.
Salami, pepperoni, etc