WPGraphQL
This FREE plugin from @hsimah adds support for the http://MetaBox.io Relationships field to WPGraphQL (when also using his wp-graphql-metabox plugin)
This FREE plugin from @hsimah exposes fields registered using the popular http://MetaBox.io to the WPGraphQL Schema.
This FREE plugin from @hsimah exposes filters on WPGraphQL queries to allow for faceted search with FacetWP