No Switch-exclusive story content exists. The “exclusive” tag in NSP circles often just means “this update arrived first on Switch” or “bundled with DLC on cart.” If you see a claim of “new levels” – that’s false. Only Horde Mode is new.
This guide is for educational purposes. Installing NSP files requires a hacked Nintendo Switch (preferably an unpatched Erista model or a modded Mariko unit). Piracy is illegal; only install updates for games you legally own. carrion switch nsp update exclusive