alt Hacker NewsI have no means to verify this, but I believe updates for Switch carts are saved to the cards rather than in the system NAND. And this makes me think, Nintendo's mistake in allowing the key cards was that it did not allow the same with the key cards that customers would still hold the physical static electricity in the card so long that the card was used at least once.
They are definitely saved to the system NAND and the carts are immutable.
I don’t understand the second part. Game key carts physically cannot fit the game or its updates, that is the entire point of their existence (storage is expensive, keys are tiny).