Where I work, we primarily use Ceph for the a K8s Native Filesystem. Though we still use OpenEBS for block store and are actively watching OpenEBS mayastor
I looked into mayastor and the NVME-of stuff is interesting, but it is so so so far behind ceph when it comes to stability and features.
One ceph has the next generation crimson OSD with seastore I believe it should close a lot of the performance gaps with ceph.