What would be major categories of food for those serious about a particular diet plan?

Are you asking for us to list what we'd do in order? Or list what I think is important?
GF is a specific type of diet, and I'd also look for LCHF.

Well I'd take vegetarian off the list since there's no real health value to it. You just have to work twice as hare to get the necessary amino acids you need for a good well-balanced diet.

It might be difficult to locate nutritious snacks that fit into your diet when you're on the road. Most convenience stores and fast-food restaurants feature unhealthy, high-sugar, high-calorie selections. But have no fear, we've got you covered! We'll go over some of the best diet snacks for while you're on the run in this blog post. We'll present a list of healthy snack suggestions as well as packing suggestions. These snacks will keep you on track whether you're going to the gym or traveling for work!
Read More Here :
https://blanddiet.net/diet-snacks/