The GHGSat constellation's payload software is still mostly OCaml, although a limited amount of newer from scratch components are indeed in Rust. It's been working well and on 16 satellites now - but as you said the main challenge has been training developers to Ocaml and I doubt they would write new code in it now.
Why do I never hear about these kinds of opportunities? I have done some Ocaml, quite a bit of embedded systems, and these days I have to waste the years doing web development.
Where do I have to call to be considered for doing OCaml embedded systems?
And it was only 3-4 years ago (maybe less) that Rust was considered by hiring managers to be in that category, too. Ask me how I know.
I'm going to assume it really means that they can't find people who satisfy some other constraint (location, pay band, "required" degree, experience on some other system or in some industry, etc) and OCaml or whatever.
In any case, LLMs blunt this. Hell, please stop me from opening a tab and starting a new OCaml project right now.
The pool is already small, and gets reduced even further.