A Table of Contents instruction that works across all markdown implementations would be an accomplishment. OTOH, Markdown does not require newlines between lis

A Table of Contents instruction that works across all markdown implementations would be an accomplishment. OTOH, Markdown does not require newlines between list elements; which is more compact but limits the HTML that can be produced from the syntax. MyST Markdown adds Sphinx roles and directives to Markdown. nbsphinx adds docutils (RST) support back to Jupyter Notebooks. (IPython notebook originally supported RST and Markdown.)