Paleo and the Camino have yet to come together. All sorts of fish and meats won’t be a problem (curd, fresh or canned) but veggies are likely to only make ot on your plate of you order an ensalada mixta (tuna and hard boiled eggs as a bonus) or if you buy them and prepare them yourself.
Breakfast will be a challenge, as it is usually yogourt, bread, croissant or chocolate croissant or some magdalena sponge cake. Tortilla de patata can make a nice 2nd breakfast or lunch, but it’s potatoes.
Lunch is ensalada mixta, but also a whole lot of bread witha tiny slice of ham or cheese.
You could: prepare hard boiled eggs, buy some cured meats and/or cans of tuna, sardines or tuna salad mixes. Depending on when you are walking (as is summer heat) you will find gazpacho sold in milk containers. Carry a few babanas, oranges, and nuts. Nuts are easy to find but expensive.
Deserts will also be an issue as they are typically yogourt, nata or flan, so milk based dishes.
Pilgrim menu is typically a pasta dish or ensalada mixta as a first dish, a slab of pork or chicken, fried or panned, served with French fries. If you are ok having your main meal mid afternoon, consider the menu del dia, it may offer better choices.
Ah, and then there is also the revueto that can be a solution: scrambled eggs with mushrooms, ham, shrimp, what have you.