Let’s be direct: using a from unofficial sources is piracy unless you have dumped your own copy from a legitimate cartridge or eShop purchase. Nintendo actively bans modified Switch consoles that go online with pirated content.
Splatoon 3 (Nintendo Switch) receives periodic updates and paid DLC that add stages, gear, weapons, quality-of-life improvements, balance patches, and limited-time events. On Nintendo Switch, official game updates and DLC are distributed through the Nintendo eShop and applied to the cartridge or digital copy. NSP files are a format used for Nintendo Switch game dumps/backups; installing or distributing NSPs outside official channels typically violates Nintendo’s terms of service and may be illegal in many jurisdictions. splatoon 3 switch nsp update dlc link
Purchase and download via the Nintendo eShop or the Expansion Pass page . NSP Files and Modding Nintendo Switch NSP Combination Install Tutorial Let’s be direct: using a from unofficial sources