After having another look at LogicalDoc, I think I may have found what I'm looking for - even though it's not as monolithic a solution as would have been "perfect".
LogicalDoc CE runs as a docker container and uses "about" 2GB of RAM (right now I'm investigating a slow memory leak, might need to restart it every 24h). You're able to ...
You should also take a look at Sphinx
it is phython-based, and runs on multiple platforms (Windows, Unix, MacOS, Docker)
Output formats: HTML (including Windows HTML Help), LaTeX (for printable PDF versions), ePub, Texinfo, manual pages, plain text
Extensive cross-references: semantic markup and automatic links for functions, classes, citations,...