Kata just released a new version, it is the only thing that I've found easy to setup with k8s... though my experience running Docker-in-Kata hasn't been very good.
We were looking at Kata as well, especially as an 'easier' firecracker, though I forgot why we didn't go further, and I've been curious why they seem to get little attention in practice
I believe part is portability, as they may require nested virtualization features to be available, and maybe QEMU overhead. Maybe also something about use in China vs elsewhere?
[1] https://github.com/smartxworks/virtink