Thanks for a great app and always brilliant blog posts.
I have a suggestion for this app involving the R-hub CRAN source code mirror of each CRAN package.
https://github.com/cran
https://docs.r-hub.io/#cranatgh
The helpful features of these package repos is that versions are added to repos as single commits and they also git tag the versions.
This enables you to see the diff between the source versions of packages using GitHub's features. For example, either by looking at the URL for the commit, like the example R-hub give here, or by using the repo's /compare page, the syntax for which is programmable
https://github.com/cran/{pkgname}/compare/{tag1}...{tag2}
(There's more about the syntax here and here)
For example, to see the diff between rmarkdown versions/tags 2.13 and 2.14 I can go to the following URL (which GitHub seems to format in markdown as cran/rmarkdown@2.13...2.14)
https://github.com/cran/rmarkdown/compare/2.13...2.14
You you could add such a URL to your results.