I have to be honest and tell you that try to load such an heavy runtime as a scripting layer is not a great idea; at the same time I can tell you that I am working on another Rust project where I also needed scripting, and after three attempts I landed on rhai (https://rhai.rs/) (https://rhai.rs/book).
You might find it nice for pretty much all use cases except for high-performance scripting (so, if you are not try to build the entire logic entirely in rhai, you are going to be fine).
I was just going to suggest rhai. It's simple enough LLMs can easily write it with a little context, and you control the entire API so you can sandbox effectively without needing to resort to hacks with a JS interpreter etc.
Yeah, it's been a bit of a dead end. I didn't want the heavy runtime but felt it was worth disproving after experimenting rather than ruling out off the bat. Even before getting it running, the dependency list alone was pretty discouraging, especially given the storm of supply chain attacks these days.
Rhai looks nice, I'll take a look, thanks! And good luck with Zerostack.