May be a stupid question, but I saw someone on Instagram using the Edizon thing and giving himself loads of stuff in Animal crossing and was just giving it away. How come he got away with going online?
It's safe to go online, just don't add that guy if you are worried. Chances are that no one has reported him for cheating and thus he's been able to keep staying online (if he hasn't already been banned by Nintendo.)
The main consensus is that you can go online with a hacked switch using clean NAND, but emuNAND CFW kept offline or using something like 90DNS. Cheating is a separate issue and you are likely to be banned for it.