Are you kidding? By the time you get through the first half of the requirements document of most windows customers, OSX and Linux alternatives have already been thoroughly ruled out.
It seems that both RHEL [1] and Ubuntu Pro have docs on FIPS, so it looks like the distribution vendors have thought about this problem, at least for paying customers. Might you be able to sketch out what the problem with FIPS compliance on Linux is?
Oh I know about this, but tell what’s simpler: Embed wolfssl per app / make it work with openssl as a module (for system wide usage) or turn a registry key to true?