The Haskell philosophy is easily misunderstood. It's not really that shared mutable state is evil but that it's difficult and so should be treated seriously and explicitly. The language still supports it—quite well. GHC's green thread scheduler is top-shelf. The main author of the GHC runtime wrote an excellent O'Reilly book called "Parallel and Concurrent Programming in Haskell" (which you can read for free online).
Was going to say exactly this. Major common misunderstanding about even Haskell. Mutable state has to eventually be a part of basically every program that does something useful. The Haskell philosophy is more about having an explicit and predictable boundary between the pure and effectful parts of your code/system.
Though you'd be surprised at how much you can do while forgoing mutable state entirely.
https://simonmar.github.io/pages/pcph.html
Of course that's not to say that Haskell is optimal for your work in embedded systems!