Github is able to list projects dependancies for some ecosystems : https://help.github.com/en/github/visualizing-repository-data-with-graphs/listing-the-packages-that-a-repository-depends-on#supported-languages
This could be really usefull to easily track project dependancies and vulnerabilities or to track the number of project using a specific lib on github.
The platformio.ini file seems easy for github to track and they do the same thing with other ecosystems, why not platformio.
I think this features is dependent to github choice, so I make a feature request to github to support Platformio.
Perhaps, if all of us request it to github we could make it work! you can do it by sending messages here.