An uncrustable is two distinct pieces of bread that have been pinched together. Personally I'm not sure I'd qualify chicken tendies as two distinct pieces of bread(ing) 🍗
I'm talking nuggets, but the concept is the same. You're right that it's not two distinct pieces of bread. It's thousands! Muahahaha.
But for real if an uncrustable, an open face sandwich, a hamburger (and with it, its low-carb bun-free version), and an ice cream sandwich all count as sandwiches, then bread is a suggestion, not a requirement.
I will however amend my earlier statement. There are foods that aren't a sandwich. Some ARE soup instead like you said.
Anybody got more semantic paradoxes to share? Or whatever these are.