Is a hotdog a sandwich?
I thought about this a lot recently after someone said it, my opinion is that
No, a hotdog is not a sandwich because it is meat inside of a single piece of bread. If you accidentally broke the bun into two pieces you could argue that you've made a hotdog sandwich because the meat is still called a hotdog and you've got two pieces of bread. That some sub sandwiches are a single nearly split piece of bread I view as an implementation detail moreso than a defining characteristic and not enough to say that sandwiches can be a single piece of bread.