There is an implementation of GraphQL for Wikimedia at https://graphql.wmflabs.org/ .

This project is to create a reading experience as a one-page Web app that loads pages from the GraphQL server and displays them. Clicking on a wiki link should load that page. Clicking on an external link would load the page in a new tab/window.

Ideally this would highlight benefits of GraphQL, namely loading the page and any extra data (links metadata, media links metadata, contributor metadata) in one request.