BSD/OS is a commercial, closed-source operating system produced by Wind River that greatly resembles the open-source BSDs. Some hardware manufacturers will not release specifications for their hardware unless the recipient signs a non-disclosure agreement (NDA). These NDAs are anathema to any open-source development project. Wind River will sign these NDAs and include reliable drivers for this hardware in BSD/OS.
If you need to run particular server-grade hardware, and it isn't supported under OpenBSD or any other open-source BSD, you might investigate BSD/OS.