The following are the queries available for the Metadata GraphQL.
Packages
packages( filter: PackageFilter! first: Int after: ID orderBy: PackageOrder ): PackageConnection!
Versions
versions( filter: VersionFilter! first: Int after: ID orderBy: VersionOrder ): VersionConnection!
Files
files( filter: FileFilter! first: Int after: ID orderBy: FileOrder ): FileConnection!