I think that's the big divide in templating languages— whether or not you trust the template author. Zero trust is a template like Liquid which has some trivial scripting stuff, but nothing non-halting (written originally for Shopify, where storefront owners could completely customize their look & feel).

And total trust is PHP.

In the middle is the whole realm of somewhat-trusted, where the templates can embed varying degrees of executable script, but you are at pains to let users know that too much embedding is a bad practice, and that especially if they're "just a designer", they should work with someone from software team to implement a properly-encapsulated solution for whatever it is they want to do.

I use PHP for exactly this reason. I wrote my own single .exe binary (written in C++) that generates JSON files from markdown files + others. The JSON files are then turned into static files via PHP using whatever template I care to create.

I think people their life harder when they go out of their way to avoid using PHP when really it is suited towards these types of problems.

I mean, it used to literally stand for Personal Home Page, so it sounds like you're using it for its original purpose.

It drives me nuts when people implement template languages on top of PHP. That was its purpose.

racket scribble might be of interest to you. https://docs.racket-lang.org/scribble/

Clojure hiccup: https://github.com/weavejester/hiccup

Python has had mako for a long time, which does this.

JSX seems to fit that bill, and many other languages have a comparable library.

JSX (or even MDX) might fit the bill!

Careful, you might end up with PHP.