You might want to consider getting one of those collapsible, portable coolers, into which you can put a blue ice pack and any kind of cold (not frozen) foods you want. I never go anywhere without my portable cooler.
But if you can’t do that, I would suggest peanut butter sandwiches, nuts of all kinds (macadamia, walnluts, pistachios, peanuts, cashews etc.)
Then there is the dried fruits (including freeze dried fruits, which are crispy as opposed to chewy)
And breakfast/energy bars (make sure you check the labels because many of them contain fish oil) I like Kashi and Luna and Cedar Lane and Health Valley.
Of course there always fruit: bananas, apples, pears, nectarines, oranges, and tangerines.
They also make hummus that comes in a jar or a pop top can (but you would need to eat all of it in one sitting, if you don’t have a cooler). You can put it on crackers, pita bread or rice cakes. I’ve also seen baba ganoush in a pop top can.
Then there are all sorts of chips (some better than others, like Sunchips and sweet potato chips, veggie chips) pretzels, bagged popcorn, corn nuts, dried wasabi peas, seaweed snacks, crackers and rice cakes (plain or flavored).
They also make applesauce and pudding in single serving cups, but you would have to eat them at room temperature (which doesn’t bother me).
And if you are interested in more entree-like foods, Trader Joe’s and most Indian markets carry a whole bunch of “vacuum packed” foods like Channa Masala and Palak Paneer and Basmati rice pilaf, but you would have to eat them at room temperature (which is totally fine with me) and you would need some type of bowl receptacle to “squirt’ them into.
If you aren’t that interested in “eating per se” but want to make sure to get your nutrition, get some six packs of Ensure, or Target’s own brand of equivalent nutition drinks.
You can also make some oatmeal cookies before you head out, and I love almost all of the fake meat jerkies I have seen at Whole Foods and other health food type of markets.