It is impossible to discuss NSP files without acknowledging the elephant in the room: Piracy. Downloading an NSP file for a game you do not own is illegal. It is the unauthorized distribution and consumption of copyrighted intellectual property. Square Enix invested money in the port; Nintendo invested money in the platform. However, the ethical waters become murky for those who do own the game. Is downloading an NSP of a game you physically own ethical? Is it ethical if you own it on the PS4 but want the portable Switch version? The internet has debated this for decades, but the law is clear: the distribution of NSP files is copyright infringement.
If one were to bypass the legalities and examine the file itself— Final Fantasy X HD Remaster on the Switch as an NSP—how does it perform? final fantasy x switch nsp