I have being studying for other Methods to use here and starting to understand what is possible in talk.tiddlywiki. It is quite broad, and underused.
I would see value in developing a proper tiddlywiki markdown standard and adding it to those available in pandoc because if we do this once we then allow for
(← = conversion from; → = conversion to; ↔︎ = conversion from and to)
That’s cool. Pandoc is written in Haskell We would need someone, who knows Haskell and the Pandoc project well enough to implement a new wiki-language. – Good luck.
Of note, in TiddlyWiki we can see the Raw HTML preview of content in a tiddler preview, this can be copied to a tool that converts HTML to Markdow and other formats for example HTML to Markdown Converter.
I have tested
talk.tiddlywiki to tiddlywiki into a markdown tiddler
First you need to identify what the social media environment accepts, sometimes it will accept html, or content simply copied and pasted and it uses as much as it can.