Kubernetes has nothing to offer to anyone that wants to work with storage (but there's a myriad of CSIs).
Here, let me give you an example of a system that offers storage in a similar way to how Kubernetes offers... well, it isn't really that good at offering compute, but, at least it kind of does it. So, Ceph -- that's something that makes sense to run PostgreSQL on (it's a storage provider). Kubernetes isn't a storage provider. It doesn't know how to manage it even...
I.e. if you think that you run PosgreSQL on Kubernetes -- you are mistaken. Something else does it. Kubernetes is a proxy there, at best (but probably is completely irrelevant).
Kubernetes has nothing to offer to anyone that wants to work with storage (but there's a myriad of CSIs).
Here, let me give you an example of a system that offers storage in a similar way to how Kubernetes offers... well, it isn't really that good at offering compute, but, at least it kind of does it. So, Ceph -- that's something that makes sense to run PostgreSQL on (it's a storage provider). Kubernetes isn't a storage provider. It doesn't know how to manage it even...
I.e. if you think that you run PosgreSQL on Kubernetes -- you are mistaken. Something else does it. Kubernetes is a proxy there, at best (but probably is completely irrelevant).