A taco is mutually exclusive from a sandwich, because it’s made from folded piece of bread, rather than sliced / partially sliced which is what defines a sandwich.

Hot dogs and subs are sandwiches for this reason, as are burgers.

Also, “taco” is a term for a specific kind of folded bread dish - even quesadillas aren’t considered tacos.

A pie is not a sandwich, taco, or quesadilla. It’s a pie.