There's a reason the original got deleted. Shit like this is the result of credit card fraud. Some dude buys come CC info on the dark web or something, buys a bunch of shit, sells it cheap as fast as possible, and makes out with the money before the banks sort everything out and revoke the money sent to the companies the thief bought shit from to sell.
For sites like G2A buying PC games, there's generally no consumer risk as Steam forces developers to pay for the lost money. Nintendo does not, and they have banned people for using eShop codes from sites like this.
I unironically browse reddit and the Nintendo Switch deals subreddit- this shit is not popular on there. This is a really shitty attempt at grassroots marketing for a literal scam.