Update: I did, indeed, get the Amazon code from preordering a game. It came in my email the next day.
We’ve heard murmurings of this summer campaign on fan sites and Reddit, but now it’s officially released. If you purchase $19.99 worth of items (shipped and sold by Amazon) in the Amazon video games section, you will get a FFXIV code for 6 cosmetic items that were previously unreleased in NA.
Be sure to check to see if the game has the promotion listed on its page before purchasing. It’ll look something like this:
I wasn’t sure if this would apply to pre-orders, but I got this from the Pokemon Sun page, so it seems to work. I was going to pre-order Sun anyhow, so I decided to take the plunge with this offer on top of it. Gotta have that white chocobo!