And they are not.
For most Halal products the goal is to have NO pig fat in them ~ which, because this is America, leads most Moslems who care about Halal to look for vegetarian products cooked in vegetable oils. That leads them to look for the big P that means pareve, or neutral, prepared without meat or dairy products or byproducts.
That's also of considerable interest to East Asians and others who are lactose intolerant.
Frankly, if I can't tell from the product list I'll look for Kosher for Passover which means no wheat, barley or rye (as well as a couple of other grains). "Kosher", by itself, is no guarantee that something is gluten free.
If the Passover product goes to the trouble of including ground up unleavened bread (matzo) then yes it still has gluten.