Warning: The 1TB versions are 65% off their never actually used price of $300. They are only a couple bucks cheaper today than yesterday, and I opted not to buy one because that's just shady behavior on Amazon's part.
Tools like CamelCamelCamel can help you avoid getting scammed by Jeffery!
Those should all be built in to Retroarch (Dolphin for GameCube). You will need to ask a piracy community for help with Switch emulation. Emudeck will install just about everything you need except for the parts that fall under copyright.
The path Google/Reddit had was invalid, but there was a cache file there that helped me locate the actual directory (at least for my Steam Deck) and identify which layout goes with which game.
The path I found was: /home/deck/.steam/root/steamapps/common/Steam Controller Configs/{USER_ID}/config/
TIL. That's not cool.