EBay auctions that don’t have n actual product are against the rules for scam and pyramid selling related reasons. It’s a nice idea though.
People used to sell “how to copy DVDs” guides on eBay. If you bought it, they’d email you a link to DVD decryptor or other free things. EBay was absolutely flooded with this stuff because they could make as many auctions as they wanted with no actual product involved. So even a well-intentioned version of that won’t fly now.