Extended ZettelMark is nothing more than ZettelMark with LaTeK. While ZettelMark is purposely very constrained to help authors best congeal and convey their ideas, sometimes it is necessary to represent things that CommonMark just cannot handle, such as mathematics. The academic world has long since solved this issue with LaTeK, the de-facto standard for academic publishing and the unofficial main additional language to Markdown supported by Pandoc Markdown, (which is so standardized it was chosen as the official documentation language of the R programming language). The Golang goldmark Markdown parser also supports LaTeK by way of KaTeX math.
Keep in mind that by using Extended ZettelMark that GitHub will be unable to render your LaTeX extensions when viewing your files from their web interface.