This is the standard file format for digital Switch games. When looking for the Final Fantasy IX NSP , you are looking for the base game.
This version is based on the mobile/PC remaster rather than a direct emulation of the PS1 original, resulting in several "deep" gameplay changes: final fantasy ix switch nsp jpn usa update upd
In the launch version, the world map and battle music restarted from the beginning after every single random encounter, preventing players from hearing the full tracks. This is the standard file format for digital Switch games