I know we’re not supposed to really even TALK about proprietary
software in FOSS communities like this one, but I can’t help but wonder
if someone might consider making (an) Emacs plugin(s) that allow(s) a
user to export Org mode files to Microsoft Office file formats such as
.docx, .xlsx and the like? Or is/are there already (a) plugin(s) in the
MELPA that can do this?

FWIW, someone calling himself "kawabata" on github has written this
pandoc-based exporter, which does an okay job for some documents.

The fly in the ointment is that this person seems to have dropped off
the 'Net : his code hasn't been maintained for three years and 35
issues are currently open. Maintaining it might be an "interesting"
project...

Getting "good" results in ODT seems easier. You have to pay attention
to some details (e. g. the "right" value to set the symbol used to
export code fragments, etc...), but at least, LibreOffice supports
vector graphics... The most important point may be to create a "good"
template document for your needs.

I have been able to create documents exporting citations, Sagemath-
generated LaTeX  math, figures, tables, listings and cross-references
to these elements to ODT, LaTeX/PDF and HTML with not much hassle
(though the ability to create a list of figures is sorely lacking...)
using the built-in ODT exporter and org-ref or citeproc-org. As already
mentioned, LibreOffice can easily convert from ODT to DOCX (with often
results superior to Word's interpretation of ODT...).

I have great expectations on the upcoming citation/bibliography system
discussed here a short while ago.

HTH,

--
Emmanuel Charpentier