@hakerdefo if you're referring to libreboot grub, it won't overwrite that.
openbsd has a framework in their kernel that allows them to re-use driver code from linux. their intel gpu driver is based upon that, and it's excellent. flawless.
openbsd's own bootloader is what you should use, if you want to dualboot. dualbooting with linux is much easier on coreboot because you can just stick grub in flash and boot linux with that and load seabios from grub to boot openbsd.
(that's what i would do)
@hakerdefo as for software availability, they do have less packages than say, freebsd or debian, but they pretty much have almost everything you can think of. thousands of ports. i've yet to find anything that is not easily possible in openbsd.
anything they don't have is a port that tech@openbsd.org would very much like you to submit :)