I would suggest getting a book called Thinking Fast and Slow, and reading it slowly and deliberately, less than 5-10 pages a day. It not only tells you how to find these kind of fallacies but also why you’re likely to fall for them and how.
Hope you have a good trip :) I know the struggle! I’m a vegetarian and often it’s very hard for me to find dishes I can eat in many countries. I have shifted towards renting Airbnbs with kitchen and making rice or pasta with local veggies for most of my meals for this reason.
You can get prepackaged meals that you can eat after submerging the packet in hot water for a few minutes. Hot water is easily available in most place, even more so if you carry a flask.
Protein bars are filling and quite nice to eat. Dried fruits like apricots or dates are also a nice calorie rich option. Bread and jam/pb are the usual travel staples. Milk powder and cornflakes/cereal is also an option, but not one of my favourites.
You can also carry out forms of bread like pretzels, bagels or focaccia which will last for a few days or even more.
Don’t forget that experiencing local food is part of any travel experience :) you’re not going to travel to Iceland to just eat in the future. So it might be a good idea to explore local supermarkets for some local fruits, bread, snacks and so on. Hopefully some Icelandic person will chime in with more suggestions.