myntric

There is actually a distro called Comixwall out there that did exactly that. I won't advocate or recommend for productio-use because development has been very slow due to the author relocating for work, but the overall concept (OpenBSD, pf, altq, etc.) is nice. I recently heard from the author and made several code recommendations for bug fixes, so I'd imagine a new release is in the works with some updates eventually.