I think there's tooling for doing something like this reverse dependency trick in nixpkgs. I made a change to pre-commit and somebody more in-the-know than I stopped by the PR and pointed out the two python packages that my changes broke.

Zero wouldn't have been surprising to me, nor would several hundred, but two... what a conveniently actionable number.

It has me wanting to give names to some of my hacks and publish them as packages so that people are more more aware when their changes are breaking changes. On the other hand, if I do something weird, I don't necessity want to burden others with maintaining it. Tradeoffs...