The problem is that the PDF layout was done entirely in Google Docs, which as far as I'm aware doesn't support "proper" bookmarks. That means a bookmarked version is a big if for the future, but we'll see what we can do!
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You can export a GDocs document and generate the PDF from LibreOffice, that should have bookmarks. Or maybe there are tools to do this automatically: https://stackoverflow.com/questions/30304718/create-bookmarks-into-a-pdf-file-via-command-line