I mean that really depends on the country, but I was talking how that usually is in my experience. In Germany you have to own the original medium of a backup and according to a quick google search same for the US.
Schmeckinger
joined 2 years ago
Its legal as long as you don't sell the original game. And as long as you don't do that there isn't a problem either. The issue stems from copying a game, selling the original and still use the copy. If no 2 copies of the same cartridge are online at the same time then there is no issue.
If you give away the card to your kid just leave your switch in airplane mode and you won't have a problem. But even so it's not allowed to do that. Btw you can also do that with a digital copy to lend it to another switch while in airplane mode.