itch.io does not provide hosting for any back-end infrastructure for games. We only let you upload your code to be executed on the end user’s computer (via a downloadable executable, or a browser based game). If you have infrastructure needed to support your game then you are responsible for hosting it.
Additionally, although blockchain projects are not explicitly banned, they are generally looked down upon by our community due to the prevalence of scams and exploitation. That is why you probably don’t see many projects related to blockchains or NFTs here.