It appears that the Metropolitan Museum of Art in New York City has at least one Vendel period disc-on-bow brooch that may have been made in Norway. It is about 20 cm long and looks as though it contained enameled plates, though those are now missing. Information about this brooch can be found here. But there seem to be more examples found in Gotland (or at least more examples of which there is information on the Internet) than in Norway. Still, this information provides food for thought.