To create a VI workload domain with VMFS on FC storage, the hosts must be commissioned with VMFS on FC as the storage type and must be associated with a vMotion only or vMotion and NFS network pool. https://docs.vmware.com/en/VMware-Cloud-Foundation/5.0/vcf-admin/GUID-4EBF9094-F732-4800-86FF-30C5D88B9758.html To deploy a VI Workload Domain with VMFS on FC storage, the hosts must be associated with a network pool that contains the vMotion network information. This is because the vMotion network is required for adding a host to the SDDC Manager inventory and for migrating workloads between hosts.
A NFS only network pool, a network pool with vMotion and iSCSI, or an iSCSI only network pool are not valid options for deploying a VI Workload Domain with VMFS on FC storage. These network pools are used for different types of storage, such as NFS, vVols on iSCSI, or vSAN.
The references are:
Network Pool Management, section "Information Required for a Network Pool" Hosts | VMware Cloud Foundation API Reference Guide APIs, section "The hosts, if intended to be used for VMFS on FC, domain must be associated with either a NFS enabled or vMotion enabled network pool."