I haven't done this since I can just pick toppings of the pizza, but I hear that there are plenty of pizza places (mostly mom & pop type Italian restaurants) that if you ask, they'll bake the toppings on a piece of foil or parchment, or bake them in an oven-proof foil pan. That means there's really no need to ask for a LC or keto meal (and hope they understand what makes it LC or keto). Or if you don't need to avoid any contact at all with gluten, just pick the toppings off the pizza to eat.

There's always key words in the menu description that you can easily figure out refer to sugars or starches - anything served with a "sauce" will almost always be sweetened and/or thickened with some kind of starch. Gravy is obviously thickened with starch. Pasta is obvious. Crispy coating, or crusted - almost always refer to breaded or battered. Breaded - obvious. Glazed - usually sugary. BBQ - in many parts of the country that refers to a sweet sauce. Seasoned can be a bit inconclusive as a description, but if it says savory seasoning, it's usually not sweetened.

This is what makes demanding a specifically vegan meal at a restaurant so silly - find something on the menu that's all plant matter, even if it's just a green salad with oil and vinegar dressing - and there's your vegan meal, no different than if it was listed specifically as being a vegan green salad on the menu.

I get the feeling that a lot of vegans just like he idea of not ever eating an animal product, but don't really understand what is (or is not) an animal product, so they need to have it spelled out for them on the menu.

For instance, I've never seen a seasoned salt that had any kind of animal matter in it - and yet Trader Joe's sells a seasoned salt that specifically says it's chicken-less, even though it's totally unnecessary to state that it's chicken-less when seasoned salt has always been chicken-less. It's as if they either can't be bothered to read the ingredient list, or if they are reading the list of ingredients, they don't know that ingredients such as paprika and turmeric are (and have always been) derived from plant matter.