If I understand correctly AppEngin uses containers that do not re-use processes, so not serverless according to the above classification.
I wonder why AppEngine didn't take off, the best answer I heard was that the security sandbox was too small and people wanted more flexibility. What do people think?
BTW As for Functions-as-a-service (FaaS) we're thinking about running the Lambda code (which is open source) on Kubernetes https://gitlab.com/gitlab-org/gitlab-ce/issues/43959#note_74... how hard would that be?