Game-key cards are different from regular game cards, because they don’t contain the full game data. Instead, the game-key card is your “key” to downloading the full game to your system via the internet.
Pay a premium for a physical copy of your game, and the cartridge may not contain the actual game. Only on Nintendo Switch 2.
I don’t like the idea of a game that can’t be played long after the servers have gone down.
But I’m glad that it can still be traded or sold after purchase unlike what Xbox tried to do.