I always feel like Tableau lacks a bit in providing metadata about data sources. I do not think its easy to find all the extracts corresponding to a data source unless you know how to hack the .twb file corresponding to your viz.
If this post assists in resolving the question, please mark it helpful or as the 'correct answer' if it resolves the question. This will help other users find the same answer/resolution. Thank you.
Have you tried using the REST API Query DataSource Connections?
Hope this could help