Users with hacked consoles often dump their own keys from their own system memory (NAND) using homebrew tools and transfer them to their emulation setups. This is the only legally defensible method of possession.
The most reliable method to get authentic keys matching your firmware is using : Enter RCM : Put your modded Switch into Recovery Mode (RCM). prod keys v2101 link
These keys are required to decrypt game files (ROMs) so they can be read by an emulator. Users with hacked consoles often dump their own