Web4 is a gateway to the smart contracts deployed to NEAR protocol.
This demo just shows the minimum viable application that lives on NEAR chain, and thus anyone hosting the gateway can serve all the Web4 projects!
See it live on testnet: https://hello-web4.testnet.page
When you deploy on mainnet, you should be able to use https://ACCOUNT_ID.near.page as your gateway.
See near-sdk docs for the prerequisites, and then build the contract using cargo-near extension:
$ cargo near build
$ cargo near deploy