I would really, really like a book-length overview like Smith's "Software Build Systems" https://isbnsearch.org/isbn/9780132171939 but for package management and package managers - something that compares and contrasts existing examples at a design/architectural/needs level and provides a framework for thinking about the entire class of problem.
@gvwilson Until this happens, the Package Management devroom track at the upcoming #FOSDEM26 might be useful, as well as some of the talks at the #HPC, #BigData, and #DataScience one:
https://fosdem.org/2026/schedule/track/package-management/
https://fosdem.org/2026/schedule/track/hpc-big-data-data-science/