Since your target is so restricted it has trouble fitting Lua, one of the smallest scripting interpreters, I suppose it does not fit the editor either, does it? Therefore there is a tool on user's desktop that pushes the scripts to the target. And this tool could compile them.
For that, Rust would make sense, because if you restrict (in the tool) use of unsafe and restrict the interfaces you make available, the user should not be able to break the system while still doing what they need and without any interpreter on target.
Paper: System Programming in Rust: Beyond Safety might be relevant. Unfortunately the paper itself seems to have disappeared, but the wayback machine still has it