OmniOS has had an emu zone brand for a while - running qemu in a zone the same way that bhyve is run in a bhyve branded zone.
I've just added the emu brand to Tribblix. I'm sure the brand framework as a whole is working - with it I can boot up Tribblix under qemu in a zone just fine. But that's x86 on x86, now need to work on getting aarch64 and sparc guests booting (and most importantly being able to access some form of console).