The term serverless is a bit overloaded. Here's what we want. (1) Ray users should be able to focus only on their application logic and not have to worry about configuring clusters at least in the common case (this is not saying that they can't configure clusters if they want to). (2) In addition, we want Ray applications to be portable and to run on different size clusters with different instance types on different cloud providers or k8s or your laptop or anywhere. The application should be decoupled from the cluster configuration. (3) Great support for autoscaling Ray clusters. When a Ray application needs more resources of a certain type (CPUs, GPUs, memory, etc), those resources should be added to the cluster. When they are no longer needed, the cluster should scale down.
This is quite different from FaaS, though seems in line with the spirit of serverless. And these "serverless" properties are not something we think of as separate from Ray, but rather as part of just making Ray work better.