(So, I've been working on this since December, and for the tiny scope, it certainly took a long time to get it out. Even now it's still rough around the edges, so feedback is very much appreciated, especially regarding docs.)
sksg is a static site generator that's inspired by the Unix philosophy of gluing smaller tools to do one large thing.
The core of sksg will just locate your pages and create the appropriate "pipelines", while the actual page generation logic happens on the other tools, (which don't need to be designed for sksg specifically)
One advantage of this is that you aren't locked into a specific language's ecosystem, as everything that supports stdin/stdout can be used as a pipeline step (including shell scripts)
There are also some simple tools distributed alongside sksg to get people started. However, they might not be as polished or as "batteries included" as one might expect.
If this sounds interesting to you, feel free to check it out here