Leak seems to include Golden Sun, Pokémon Pinball among others.
Earlier today four files were leaked to 4chan. This contains 2 NSPs (Nintendo Submission Package: contains all of the files and data needed to display icons, a title and a game) and a 7z archive that has loose NCAs (Nintendo Content Archive, which contains game data dumped from a Nintendo Switch game card).
According to twitter user trashbandatcoot the 2 NSPs are a Nintendo developed GBA emulator called Sloop, and the 7z archive is a Game Boy emulator called Hiyoki, with all Game Boy games being separate applications. The emulators were developed by NERD (Nintendo Europe Research & Development) and functional.