You need the latest Switch keys to decrypt the NSP file.
Playing MHGU in 4K rather than the Switch's 1080p docked limit. 60 FPS Mods: Removing the 30 FPS cap for smoother combat. monsterhuntergenerationsultimatenspromslab+link
Centralizing your library on a single handheld device. How to Use the Link Safely You need the latest Switch keys to decrypt the NSP file
You will likely see two links. One is the Base Game (v1.0) and the other is the Update (v1.4.0) . You need both for the full experience. monsterhuntergenerationsultimatenspromslab+link
Once you have the link and the file, the setup follows a standard emulation path: