Hey @didiaps ,
Requirements for building a sales channel can be found in the previous linked documentation, and are expanded on in this getting started guide. I’d suggest reviewing those docs on building a sales channel, as it breaks down requirements, contains important steps, considerations and details.
If you are looking to build a custom storefront on a store that leverages the Storefront API to create and update the cart object, create checkouts, among other available features, the following developer docs are provide a detailed overview and helpful guides to get started. There is also a dedicated community forum for questions around these features here: Storefront API and SDKs.
Cheers!
Shopify Developer Support