Installing an NSP for an online-only game like Fortnite carries significant danger for the console: Fortnite for Nintendo Switch - Nintendo Official Site
For educational purposes, here's a general overview of how NSP files are handled: fortnite switch nsp
A: No. Even if you install the NSP, the game requires an internet handshake with Epic. If your Switch is banned from Nintendo servers, you might still connect to Epic, but the matchmaking often fails due to lack of NAT services. Generally, a banned Switch plays Fortnite poorly or not at all. Installing an NSP for an online-only game like