If you own a physical cartridge and a modded Switch (with Atmosphere), you can dump your own ROM using homebrew tools like or Lockpick_RCM (for keys) followed by NUT or DD commands. This produces an XCI or NSP that is legally yours to back up.
To start your journey, you need the base game file. On the Nintendo Switch, digital software is typically distributed in the NSP (Nintendo Submission Package) File Size: Fire Emblem Warriors game requires approximately of storage space. Format Choice: (cartridge image) files are also common, Fire Emblem Warriors Switch ROM NSP UPDATE DLC
Each pack also includes new powerful weapons, blessings, and Anna’s Mementos for unlocking rare materials. If you own a physical cartridge and a
Downloading NSP/XCI files and updates from unauthorized sites can expose you to: Fire Emblem Warriors Switch ROM NSP UPDATE DLC