Can I define a named query within the Shopify Graphiql app then call it from my PHP app?

In standard SQL, you can define stored procedures within the database admin, then call those procedures from your own app. At first sight Shopify GraphQL named queries are something very similar. I know how to define and run a named query within the Shopify Graphiql app, and also how to define and run a named query within my own PHP app. But I cannot find any way of defining a set of named queries within my store admin and then calling them from within my own app. Is this in fact possible?