Nintendo's big surprise was Nintendo Labo, an original concept that combines cardboard constructions with the Nintendo Switch and its Joy-Con, making interactive "Toy-Boxes". There will be several Nintendo Labo kits, and they will include all the tools and technology required (including games and software) to be enjoyed on the Nintendo Switch.
With cards and other materials, players can build certain objects, such as a piano, a doll, a fishing rod, and even a suit to control a robot. These constructions are then compatible with the console and corresponding software. Apparently, these constructs are pre-defined but will have some level of customisation.
Two kits have already been announced, and they will go on sale as of April 27. The European price has not been confirmed, but in the US the Assorted Kit will cost $69.99, and the Robot Kit will cost $79.99. You can get more info via the official website, and in the video below.