Can you use SLURM to schedule services? IE, long-running not-batch-jobs that expose network ports (often multiple)? That's what k8s (and borg) really are- service schedules, not batch schedulers.
I can run batch jobs in GKE. It looks like SLURM doesn't have a way to handle endpoints (IE, a port manager) so I agree, deployments will have to stay in something like k8s.