I've been using katex-rs, a Rust rewrite, to implement LaTeX rendering for a Rust web app. It was easy enough to hook into pulldown_cmark, so that $ and $$ and render a decent subset of LaTeX. Since pulldown_cmark is a proper Markdown parser, you listen for Event::InlineMath and Event::DisplayMath then call KaTeX directly. No regex or HTML escaping necessary. In my web app, this is all encapsulated into a single function that I can call within Tera templates. It's as SSR as it gets; no Node.js or client-side JavaScript necessary.

The costliest asset is a minified stylesheet served through a CDN. (I do this out of laziness, and because the web app as-is needs nothing more than the standard Rust toolchain).

https://github.com/katex-rs/katex-rs

Hugo includes native KaTeX: https://gohugo.io/functions/transform/tomath/

The docs recommend setting up KaTeX CSS (which requires either a CDN link or Node), but by changing output to 'mathml,' you can have the browser render equations with zero dependencies.

If your use case is generating html, MathML is supported in all modern browsers: https://developer.mozilla.org/en-US/docs/Web/MathML#browser_...

I use it in my static site generator in Python via https://github.com/rubenvannieuwpoort/PyKaTeX.

Disclaimer: I am the author of PyKaTeX.

Port it? Or maybe bundle a tiny interpreter instead of Node.