If you own the physical cartridge but want the convenience of a digital install (to save your cartridge slot for another game) and you dump your own cartridge into an NSP using tools like NUT or hactool , that is legal under "fair use" and backup provisions in some jurisdictions (though Nintendo’s EULA disputes this).
The game follows the original One Piece story from Luffy's departure at Fushia Village through the . Pirate Warriors 3 | One Piece Wiki one piece pirate warriors 3 nsp exclusive