vSAN HCI Mesh is the correct feature because the application must continue running on the existing compute cluster, but that cluster lacks enough unused vSAN capacity and has no available NVMe slots for expansion. HCI Mesh, also known as vSAN datastore sharing, allows independent vSAN clusters to share remote datastore capacity with other compatible vSAN clusters. The remote datastore can be mounted and used as if it were local storage, allowing VMs running on the current cluster to consume storage from another vSAN cluster that has sufficient capacity and performance. This satisfies the requirement without purchasing hosts, reassigning hosts, or moving the application away from the cluster that provides the required CPU and memory. vSAN Data Protection addresses snapshots and recovery, not capacity expansion. vSAN File Services provides SMB/NFS file shares, not additional VM datastore capacity. vSAN Stretched Clusters provide availability-zone resilience, not cross-cluster capacity borrowing. VCF documentation describes HCI Mesh as cross-cluster capacity sharing that enables multiple independent vSAN HCI clusters to consume storage from adjacent vSAN storage resources. Reference topics: vSAN HCI Mesh, vSAN Datastore Sharing, Cross-Cluster Capacity Sharing, Remote vSAN Datastore.