That does sound like a fun project! Though it has to be said that most of the popular static-site creators will allow custom things to be done with plugins.

I wrote my own static-blog compiler, which reads a tree of markdown files, then spits out posts, archives, tags, etc. As an intermediary form it inserts all the posts into a local SQLite database (which can be trashed and rebuilt when required), which means I can efficiently output tags, etc.

Realistically my generator isn't so different from others, but it does integrate well for my personal use and supports comments - something a lot of static blogs miss. (I literally have a CGI script which writes out comments to flat-files, then these are picked up in the build-process, being fetched via rsync first).

Source:

https://github.com/skx/chronicle2/

Demo:

https://blog.steve.fi/