Data catalogues, repositories, registers are the standard solutions to data governance and discoverability problems.
But this means the information is often detached from the places it is produced. The metadata is managed with different tools by different teams from the data itself.
The federated search approach is about searching for the data closer to the source, hopefully in the source system itself. With that, the search network needs to know about the services and could be used to make the metadata and the services searchable as well as the data itself.