Nintendo aggressively targets piracy, and using these files without owning the original game can lead to console bans (CDN bans or online service bans).
These are digital-native files, essentially the same format used for games downloaded directly from the eShop. They are the most common choice for modern setups.
: Typically larger than NSPs because they include "padded" empty space from the physical card (e.g., an XCI might be 10GB+ while the game data is only ~4.2GB). NSP (Nintendo Submission Package) : A copy of the digital eShop version.