Hello,

Long time no see. Update on the feature request: Michał Górny rejected
Florian's the pull request, raising concerns regarding the use of gentoo specific tooling;
stating that eselect-repository should work (as I understood it) as a standalone program.

Originally, Górny suggested updating the repositories.xml file by adding the masters entry.

That's why I did some data processing of the overlays. 
(It turns out only a small set of overlays have additional dependencies besides gentoo). 
With this data now processed, adding the masters entry to the repositories.xml
should be way easier.
Here's the repo: https://github.com/lima-limon-inc/OverlayStats
(it also contains information regarding package amounts by overlay,
which I found it quite interesting)
And here's a google sheet with the data loaded in: 
https://docs.google.com/spreadsheets/d/1Spti8KCFQbi0kszvgBnxMtAlUC3RU1HZU8MZHlYP5xQ/edit?usp=sharing

Having said that, there's still the issue of data duplication that Florian raised.
That I do not know how could be tackled.

Best regards,
- Tomas Fabrizio Orsi