Currently that feature is unsupported or I just can't figure out how to do it. With the latest compiler version 0.14 any .typ file I try to compile will incur warnings about skipping the equations (skipping the main reason I'd want to compile a Typst file to HTML...).

As per their GitHub they haven't included MathJax or KaTeX support yet as they were more focused on semantic and structural accuracy of HTML output with this release.