Hi @kurt-burri_8500,
I think you are looking for our [Package Consumers] (https://docs.inedo.com/docs/proget-packages-package-consumers) feature in ProGet. Unfortunately, the automated way of doing this requires a paid version of ProGet, but you can manually add the consumer records. The automated way would be to run our pgscan tool against the source code and it will record a package consumer record on each of it's dependencies.
This feature will be more helpful going forward, so it's not exactly your use case. If you have access to the source code, you could either use a tool like Agent Ransack to search the contents of files for that package Id or fork our pgscan tool and modify it to scan through your projects and output which ones are consuming that dependency.
You could also try to use the feed APIs that the client tools use to walk the packages and look for dependencies, but there is not much guidance I can give there (especially since each feed type differs greatly) and this solution can get pretty complex pretty quickly.
Hope this helps!
Thanks,
Dan