Is it the language that forces procedural code? In my experience it’s usually the stdlib, but the language itself is capable of declarative constructs outside of existing APIs. If that’s the case, an approach like “functional core, imperative shell” is often a good one. You can treat the stdlib like it’s any other external API, and walk it off as such.

There is no stdlib. Its a very specific proprietary purpose built language thats been around since like the 90s. It has a super limit set of standard functions that operate on an underlying proprietary data structure and every thing else is just a thin vaneer over a very limited set of c functions.