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.