Do Shopify CLI Tools Need to be Used for Functions in Custom Setups?

[kanyewestnewmer]

A brief question regarding Shopify Functions is needed. Do we require Shopify CLI applications to implement Shopify Functions? There is not a single website that demonstrates how to do that, despite the fact that all tutorials and documentation indicate that we may use any language (Convert to web assembly) and any setup. Our app, which was not created using the Shopify CLI, is now live on Shopify, and we want to add discount capabilities.