Suggestion: PDF can have attachments inside. Libre already can put itself documents in PDF’s attachment. Could you add functionality for fonts, docs, links and other files? Just some kind of “add attachment” menu. But if think a litle about it it can be:
Fonts automatically will be taken from system, just select check-box for it. Local footnotes for something (pictures, other docs or files) - the same automatically, check -box just.
Which LO version are you using ? Each functionality you are asking for is already available: embedded non standard fonts, links and, if you create a master document, you can generate a single pdf file with several separated text documents.
last one at this moment - 3.6.3.2, but I don’t see any attachments inside created PDFs. I even don’t see odt file in attachment, I just know that it’s somewhere in PDF. Font’s integrated too, not like simple attachment. Does links (that were cashed, URLs) included too? I see only links by itself.