I have a friend who is Celiac and also doesn't eat fish and she had a great time in Portugal. She loves roasted chicken, and there are some great ones to be found there! I was googling "piri-piri chicken" (piri piri is a spice brought back to Portugal from their African/Indian former territories) - it's delicious and in its simplest form should be gluten free - anyway, I found this blog post that might be super helpful to you:
https://www.legalnomads.com/gluten-free/portugal/
A simple meat [asado (roasted) or a la plancha (griddled)] with potato (usually fries) and sautéed vegetables you should fare pretty well.
(verduras salteadas / legumes refogados)
( Spanish / Portuguese )
[I'm glad you said that about "wheat is wheat is wheat" ... in traveling with my Celiac friend, I know what a challenge it can be because some people don't truly understand the difference between "I don't eat wheat" to "if there's even a speck of gluten in my food I will become very sick". She now says when ordering food in a restaurant "This is not a lifestyle choice; I will get sick if I eat any gluten". The good thing is that in Spain & Portugal, I find it to be that they mostly cook from scratch and don't use as many processed ingredients as here in the US, for example, so it *should* be easier to be GF there. However, it also just depends on which café/restaurant you end up in.]
Buen Camino to you!!