What do you get from boiling dough
When you boil bread dough, you get a type of boiled bagel, I don't think it has a name in English. Dumplings are more likely to be made from other types of dough, like pasta dough. And while you don't have to boil your dough in a torus shape, it is the most convenient one since you cannot shape it thick and expect to cook through.
By the way, when you fry bread dough, you don't get doughnuts, that would be a different dough (although some bread doughs like challah might produce a doughnut like result). With standard bread dough, you get mekica/Lángos.