It is possible to deploy Immuta without the use of cloud provided managed services by using enterprise-ready tools for kubernetes.
This article describes deploying a PostgreSQL cluster in the Immuta installation namespace and pointing the Immuta application at this cluster for deployment
Crunchy PostgreSQL for Kubernetes
This section relies heavily on Crunchydata's installation documentation guide found at the link below and assumes you have forked and cloned their examples repository.
PG_CLUSTER_PRIMARY_POD=$(kubectl get pod -n ${IMMUTA_NAMESPACE} -o name -l postgres-operator.crunchydata.com/cluster=${PG_RELEASE_NAME},postgres-operator.crunchydata.com/role=master)
kubectl -n ${IMMUTA_NAMESPACE} port-forward "${PG_CLUSTER_PRIMARY_POD}" 5432:5432