So, are there decent lower-level (e.g. C++ or even C) libraries for doing this, which this library wraps? Or does this actually do the nitty-gritty PDF innards

So, are there decent lower-level (e.g. C++ or even C) libraries for doing this, which this library wraps? Or does this actually do the nitty-gritty PDF innards itself? As for myself, I've not had to automate work on PDFs, luckily; for manual manipulation and annotation I've found Xournal++ sort of useful (https://xournalpp.github.io/ https://xournalpp.github.io/). Inkscape can also be used with some questionable PDFs.