There is a Harvester CSI driver, which can be used to provide volumes from the host Harvester cluster directly to the guest K8s cluster's workload. However this CSI driver is meant to be used in conjunction with RKE1/2 or K3s guest clusters deployed via Rancher using the Harvester node driver:
https://docs.harvesterhci.io/v1.3/rancher/csi-driver