When we talk about an NSP update for the Switch, we are referring to the official Nintendo submission package format used for digital content. For those who own the game digitally through the eShop, these updates are typically handled automatically by the console's firmware. When a new version is detected, the Switch downloads the update NSP and merges the data with the base game files to unlock new features, such as improved water physics, better draw distances, or the latest community expeditions.
If you are managing your game files manually or looking for specific version numbers, here is how the update system works: No Man-s Sky Switch NSP UPDATE