Slash GraphQL supports GraphQL± with caveats, refer Slash GraphQL Release July 28 2020 & Advanced Queries documentation & GraphQL+- poor support in GraphQL - #9 by pawan discussion.
RFCs:
- Implementing Geo features in GraphQL
- Supporting GraphQL+- queries in GraphQL
- GraphQL+- -> Spec Compliant GraphQL
Last one might interest @pmualaba, as @michaelcompton goes into detail about each of the feature of GraphQL± and how easy, hard, or impossible the translation to spec compliant GraphQL will be.
P.S. The answer to this question must be pinned globally IMO as it’s FAQ. I asked it several times myself! 