In this video, Jason Bahl and Daniel Olson (of getshifter.io) pair and walk through registering GraphQL connections.
In this video, they register connections to allow users to query enqueued assets (stylesheets/scripts) using GraphQL.
Since this video was released, this functionality has been brought to WPGraphQL core. Users can query enqueued assets in connection with nodes without registering custom connections.
The video still should be helpful for users looking to register custom connections in their apps.