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.
No. You have to download the game and need the cartridge to play it.
It’s not unheard of, though. Modern Warfare 2 had only a 70MB file on its disc, basically a license, and required you to download the actual game.
Note I’m not defending this. It’s a nightmare for game preservation and pushes us ever further in the direction of never owning anything. I’m just saying Nintendo isn’t breaking new ground with this particular outrage.