It seem they only support Commonmark: https://help.libreoffice.org/latest/en-US/text/swriter/guide...

So no tables, footnotes, table of content, math formulas, citations, …

So the better way to create markdown is still to use pandoc and convert your libre office documents into the much more powerful pandoc markdown dialect:

https://garrettgman.github.io/rmarkdown/authoring_pandoc_mar...