Yeah, they're not tied to accounts or consoles. Any console with the card in will be able to play the game after downloading it. You can trade or sell them.

Codes and boxes are just digital purchases with plastic waste attached and no further benefit.

They're shittier than real physical games, but they still do have that one advantage over digital games, just with the drawback that you still have a physical cartridge you have to switch out and carry around. It's a mixed bag.

I mean they're clearly not. Codes are one time use and forever bound to you, these can be sold/traded.

I'm not saying they're good. Just that there is an advantage (and disadvantages)