To respond to your question: no. Not sure why you linked me the PDF 2 specification. PDF/UA is from 2012, and the ability to tag PDF files for accessibility is a thing since 2001 (with PDF 1.4).
Various tools and packages that attempted to generate accessible pdfs from LaTeX have existed for aeons, all of they had a common characteristic: they sucked. I am convinced that by this point everyone who cares about accessibility has moved to other formats (like HTML).
"HTML does not"
<aside> is "first class".
https://www.pdfa.org/resource/iso-32000-pdf
The LaTeX project announced an a16y project in January of this year. A tool is now available, though success varies.
https://www.latex-project.org/publications/indexbytopic/pdf/
Of footnotes: LaTeX has the macro, it's common across multiple document types. HTML does not.