is available as a free download on the Nintendo Switch. You do not need to look for an "NSP" file (which is a format typically used for piracy or emulators) because the game is officially free-to-play on the Nintendo eShop. Official Download Method
Conclusion
While the game is fun and portable, the Switch version has some technical trade-offs compared to more powerful consoles or PC: Fall Guys Switch NSP Download gratis
In the meantime, you can: