SmartOS runs just fine on AMD CPUs. KVM support for AMD hasn't been merged to illumos-kvm yet (mostly just due to time), but you can do your own builds with it (https://github.com/jclulow/illumos-kvm/).

But Triton containers don't run in KVM anyway. They run natively on the OS with no VM. So you can download and run Triton on AMD today, just as you can with Intel CPUs.