Is this an xy problem? If you have the original document (in Markdown), one possibility would be to use my software, KeenWrite[1], to convert Markdown to XHTML then typeset XHTML to PDF via ConTeXt. See the user manual[2] for an example of a Markdown document typeset in this fashion, along with usage instructions.

If you only have HTML to work with, you can also use Flying Saucer[3], which is what KeenWrite uses to preview Markdown documents when rendered as HTML. Flying Saucer uses an open-source version of iText[4] to produce PDF documents (from HTML source docs).

Another possibility is to use pandoc and LaTeX.

[1]: https://keenwrite.com/

[2]: https://keenwrite.com/docs/user-manual.pdf

[3]: https://github.com/flyingsaucerproject/flyingsaucer

[4]: https://itextpdf.com/