The Sandwich Alignment Chart, created by @mattomic back in 2017, is a handy guide that'll tell you exact what is and isn't a sandwich, based on structure and ingredients.
On the x-axis, there's ingredient purist (classic toppings like meat, cheese, lettuce and condiments), ingredient neutral (containing a broader scope of savory ingredients), and ingredient rebel (like, literally any food).
On the y-axis, there's structure purist (two pieces of bread), structure neutral (a container, not necessarily in two separate pieces), and structure rebel (any food enveloped in anyway by another food).
According to @mattomic's Sandwich Alignment Chart, a hotdog is an ingredient neutral/structural neutral sandwich. An ice cream taco is also a sandwich (structural neutral, ingredient rebel). And a burrito is a sandwich (structural rebel, ingredient neutral).
But if you take things to the extreme, you'll get a structural and ingredient rebel. A pure radical sandwich anarchy that considers a Pop-Tart a sandwich!