How to expose a GraphQL datasource via HTTP for REST clients

[genesioliniantares]

Hello,
I need to expose a GraphQL data source (Azure Fabric, handled by a third-party) to a series of non-GraphQL capable HTTP clients
Let's call this a "gateway", that I would like to develop in .NET

The other requirement is to dynamically discover the GraphQL schema at runtime (startup) of the "gateway"

My idea is to expose a REST endpoint (https://graphql.org/learn/serving-over-http/) using HotChocolate MapGraphQLHttp()
Then how could I forward all the incoming requests to the real GraphQL endpoint?
in the middle I would like to authenticate/authorize the calling client and log the operations

Does anybody have an example of how to achieve this?