Could I open up a restaurant selling water, Bologna Sandwiches, and Chef Boyardee Pizzas (Cheese Only)? ?

Sure why not. They have restaurants that just have cold cereal and there's ones that have only grilled cheese sandwiches or peanut butter and jelly and they all seem to be doing well. as a saying goes it's better to do one or two items great than a hundred items s*** poor

Sure you "could" and close it almost as quick.

That would be better for a food truck than a restaurant.

Yes, you could however I doubt you would have any customers interested in ypur menu.

Most people would never eat bologna.

Could you? Yes. Should you? NO!

You could if you have the money, but it won't last for long.

You can open it... the better question is, "How long will it remain a viable enterprise?"

You'd have to get permission from the Chef Boyardee copyright owners to sell their products, and you wouldn't have very much success with such a limited menu, especially of items that people can otherwise make or acquire for themselves Someone would need a reason for getting their water from your restaurant rather than just, say, staying home and getting it from their kitchen tap.