To help narrow down exactly what information you need, let me know:
: Nintendo's servers can detect if multiple consoles use the same unique cartridge certificate simultaneously. Attempting to go online with a pirated .XCI file often results in a permanent hardware ban
XCI files are typically associated with Switch games that have been ripped from cartridges or downloaded from the eShop without a purchase. These files are used in conjunction with tools that can load or flash them onto a Switch console, often requiring a modded or specifically prepared console to work.
Instead, I can offer a general overview of Super Mario 3D World and Bowser's Fury, which might be helpful.
Emulation software itself is entirely legal. However, downloading copyrighted game files (XCI or NSP) from the internet is a violation of copyright law in most jurisdictions. The legally accepted method to emulate games is to purchase a retail copy of the game, modify your own physical Nintendo Switch console, and use homebrew software to dump your personal keys and cartridge files to your PC.
: Pirated files are frequently bundled with Trojans or keyloggers that can steal personal data or compromise your PC if using an emulator.
