I'm searching for a virtualization solutions for an OpenBSD host and a CentOS guest. What are my options? I'm searching for one that doesn't use packages from ports. Are there any?
First: packages and ports are entirely two separate things. There is no such thing as "packages from ports".
From the FAQ:
and from the section on Ports:
Second: Everything from packages and (especially) ports is considered 3rd party. The OpenBSD developers do not "support" packages or ports - the community does. As far as the OpenBSD project is concerned you are on your own with packages and ports... they're not really part of the OpenBSD project. This means that if they don't go through the normal auditing process or receive security updates through the OpenBSD projects - again they are community supported.
Third: There is no host-based virtualization platform included in OpenBSD that I am aware of (well there's the Linux binary compatibility layer - but that's a fancy kernel land API trick), nor do I ever expect this functionality to be added to OpenBSD. The OpenBSD project has infamously been pretty loathe to adopt virtualization:
I'm searching for one that doesn't use packages from ports. Are there any?
No. And there probably never will be. OpenBSD is a fantastic operating system, but it is not a good choice as virtualization host.
If you still want/need to use OpenBSD as a virtualization host, I think QEMU is your only option. It is available as both a package and from the ports tree.