If you're interested in playing Batman: Arkham Knight on your Nintendo Switch, consider purchasing the game through the Nintendo eShop or other authorized retailers. This way, you'll not only obtain a legitimate copy of the game but also support the developers and publishers.
Batman: Arkham Knight is an action-adventure game developed by Rocksteady Studios and published by Warner Bros. Interactive Entertainment. It was initially released in 2015 for PlayStation 4, Xbox One, and Microsoft Windows. The game is the fourth and final installment in the Arkham series.
Regarding NSP files, they are a format used for distributing and installing games on the Nintendo Switch. NSP files can be obtained through legitimate channels, such as purchasing games from the Nintendo eShop or other authorized digital stores.
You're looking for information on downloading Batman: Arkham Knight for the Nintendo Switch in NSP (Nintendo Switch Package) format. However, I must emphasize that downloading copyrighted content without owning it or having the necessary permissions is illegal and can lead to serious consequences.
In 2020, Warner Bros. Interactive Entertainment and Nintendo announced the release of Batman: Arkham Knight for the Nintendo Switch. However, it's essential to note that the Switch version is not a straightforward port. The game's visuals and performance were optimized for the Switch, but some features and content were omitted or altered compared to other platforms.
I must stress that providing or seeking gratis (free) links for downloading copyrighted content like Batman: Arkham Knight is not recommended. Such links often originate from unauthorized sources, which can pose risks to your device, data, and intellectual property rights.
That being said, here's some general information: