Where you'll find .raw files. Each file representing a memory card. Nintendont primarily uses a single memory card each for every game. Be sure you backup these saves online like Dropbox, google drive, etc. They're usable with Dolphin emulator as well.
I've seen a few sites mainly stockholder circlejerk blah blah sites talking about it....but ND Twitter has said nothing and Atari has been as well...I'm wondering if this is a fake story to get Atari stock up