You could check for save the world data when an account is uploaded, this would help sellers sell accounts with rare STW stuff easier and protect the customers from scams claiming the account has specific stuff it doesn't have. You can scrape stw data from fortnitedb, the data shouldn't be too hard to scrape as they have a an API, but if you don't want to pay, should be easy enough just getting the data from the profile link, https://fortnitedb.com/profile/{USERNAMEHERE}, if you don't want to use any external tools at all, you can get the data straight from the account. Whatever you do to get it, it would make it a better experience overall for both customer and seller.