This is very nice! At the risk of getting ahead of things:
I've been designing a new light markup syntax, based on the ideas in my essay "Beyond Markdown" (https://johnmacfarlane.net/beyond-markdown.html). I thought readers of this list might be interested. The language and its rationale are described here: https://github.com/jgm/djot
The repository also contains a very fast parser written in pure Lua. A pandoc custom reader and custom writer are also provided, so you can convert your favorite formats to and from djot.
The syntax is briefly described here: https://djot.net/playground/syntax.html
You can play with the implementation here: https://djot.net/playground/
John