Would there be any interest? header tags are used to make table of contents, anchor tags create Index entries, all the formatting tags (tables, un-numbered and numbered lists etc) do basic print formatting. All the bold/underline/italic also render to paper. Sort of like a poor man's TeX.
I use this one, and it's pretty nice: https://weasyprint.org/. They implement their own rendering engine so its support of new features and edge cases isn't the best, but every problem I've run into with it has been solvable with a little work. I really like it for laying out printed forms!