MSK IAM support has long mystified me. I think they only supported Java for the first 9 months or so. Even then they still don't have GO or PHP support. It's not a ton of work, they're reusing request signer code anyways.
My suspicion is that if they didn't want to bother to write a C++ client, they for sure wouldn't have the empathy(?) to document how anyone else could, too. I said empathy but I kind of wonder if by publishing how something works they're committing to it, versus they're currently only one commit away from changing it in their clients, without having to notify anyone