In Liferay's slack I was told support for GraphQL is available in 7.2 SP1 and 7.1 FP12 onwards, will be released in 7.2 GA2. But I don't work for Liferay so can't confirm this

I have also heard GraphQL support in Liferay is still a work in progress. I have a project with a golang server app handling the GraphQL api from a frontend PWA (lit-html, lit-apollo) where in turn the golang app interfaces with the new headless api . For the golang code (consuming the Liferay REST apis) I used the openapi-generator: which can generate code for many languages and supports openapi3. On my radar for the future is looking at the GraphQL in Liferay itself, but have not dove into it yet. 

Hi Gwowen,
as announced here, https://liferay.dev/blogs/-/blogs/liferay-portal-7-2-ce-ga2-release
Liferay GraphQL support has been added to Liferay 7.2 CE GA2 (recently released) and to 7.2 DXP SP1.

I have a Liferay 7.2 CE GA2  up and running but
The URL
http://localhost:8080/o/graphql
like documented here
https://portal.liferay.dev/docs/7-2/frameworks/-/knowledge_base/f/get-started-discover-the-api
returns nothing

Sorry I was wrong:
Using Altair, a GraphQL Client extension of Firefox and sending a query works fine:

query {
  messageBoardThreads(siteKey: "Guest") {
    items {
      aggregateRating {
        ratingCount
        ratingValue
      }
      articleBody
      id
      messageBoardMessages {
        items {
          headline
        }
      }
    }
    page
    pageSize
    totalCount
  }
}

https://liferay.dev/blogs/-/blogs/new-graphql-apis-in-liferay-7-2
RestBuilder tool in DXP 7.2 creates the Rest Services with OpenAPI and GraphQL support.