Mercure could be use as a transport for GraphQL subscriptions: https://github.com/dunglas/mercure#how-to-use-mercure-with-graphql

As Apollo and API Platform are very popular GraphQL implementations. It could be nice to add support for Mercure as a transport for them.

For Apollo, a new adapter inspired by existing implementations could be done: https://www.apollographql.com/docs/apollo-server/data/subscriptions/#pubsub-implementations
For API Platform, see api-platform/core#3124