But we don't know what they have unless they announce it. My guess is that they kept an ARM Zen frontend working, internally. And they probably have a RISC-V f

But we don't know what they have unless they announce it. My guess is that they kept an ARM Zen frontend working, internally. And they probably have a RISC-V frontend now, alongside many other projects. They are large enough to do so. When they perceive they can launch a successful product, they do so. Otherwise, we never know of these efforts.