we also don't know what have to prepare, what kind of wallet and blockchain (erc20 or bsc), possible the user can't sell or transfers it to another market and that NFT just available in sandbox casino only.
As mentioned by FrankBank everything needed is being prepared including the network used and other things just waiting for the announcement. I suspect these NFTs will be available on Opensea as you can see in sandboxcasino some examples of NFTs connected to Opensea use multiple networks.
as NFT concept is relatively new in casinos, we will see if sandbox will be successful in integrating this current hype within the casino itself. we don't know yet what approach they are holding here but let's see once they launch it on their platform.
sometimes it is how the team will introduce their game or concept to the gambling community, to see what kind of interest they will gain from the players.