The .rar is a container; the internal .nsp is the standard digital format used for Nintendo Switch games and emulators.
You can use tools like NSC_Builder (Nintendo Switch Cleaner and Builder) to verify the file's hash and digital signature against known legitimate copies. Sea of Stars (NSP)(DEMO).rar
A common safety practice is to test the file first in an emulator like Ryujinx on a PC before installing it on an actual Switch. Installation Context The .rar is a container
The demo on the official Nintendo eShop is approximately 1 GB . If your .rar or extracted .nsp is significantly smaller (e.g., only a few MBs), it may be incomplete or malicious. Safety & Legitimacy only a few MBs)