I've spent a lot of time on planes.

I use a cooler pack that will fit in my carryon (one of those rolling things). I put a block of blue ice for any items that need refrig like probiotic or liquid vits/mins. Also cut up some raw veggies you like. I like bell peppers and carrots, celery. If you can have nut butter, put some of that in a small container and put in cooler too. You can dip the carrots, celery, cut bell pepper it it. I eat sunflower seeds too. (usually they don't find them, even with agricultural inspection). On this note, be careful of apples if you eat granny smith. I've had those taken away several times.

It sounds like 10 hours is an overseas trip. If so, they usually serve food and usually there's a salad to munch on. If there's a meat protein, you can scrape off or use a napkin on, the sauce, if any.

I lucked out on an Air France roundtrip. They had tons of food twice each way that I could pick and choose off the tray. Lucky me! It was a 10-hour flight each way.

Also, you could cut up some firm tofu into cubes and put that in a container for the cooler. My cooler is the size that sits upright inside the rollon when it lays flat.

You can stash a can of Veg All (or other) in your rollon and throw in a can opener, then open in the restroom. You might pack plastic ware and an empty food storage bowl to mix veg and tofu together. Pre add any seasoning to the tofu.

Good luck. obj

Blanched almonds (pref. pre soaked). Very nutritious and alkalising.
Otherwise seeds (pumpkin, sunflower, linseed etc) are lovely *lightly* toasted/fried (minimal oil/cooking time) with xylitol or stevia and maybe spices (e.g. cinnamon) or a savoury version with Sea Salt .
Better yet eat them raw. Pumpkin seeds are said to be antifungal.