The best way is to plan ahead. If you're staying in a hotel, you'll probably be able to fix whatever you have at home. Nuts and fresh fruit are shelf-stable (unless you've already put the fruit in the fridge, which isn't good for it anyway).
I will buy all my foods from the grocery store as if I’m still at home. Of course these options tend to be cold options such as salad and fruits, cold meats for wraps, veggies and hummus, etc. Carrying around energy bars and nuts is great for fuel on the go as well. My favorite on the go snacks are jerky, energy bar (homemade that I will bring with me), and an apple or celery sticks.
When traveling, it’s important you free up time for a breakfast. Travelling and exploring requires a lot of energy, so by waking up early to give yourself time in the morning to eat is good. Buying fruits, nuts and eggs in small amounts to conserve waste gives you options to eat and get the proper amount of nutrients.
Flax meal chia seeds flaxseeds coconut chips with coconut milk or coconut yoghurt, or omlette or boiled eggs or even a fruit smoothie