Q: What storage is supported by Hyper-V Replica?

A: Any supported storage that can host VHD (virtual hard disk)/VHDX is supported for Hyper-V Replica. This includes direct attached, SAN storage, and SMB 3.

If a VM has iSCSI connectivity configured within the VM, this is invisible to Hyper-V Replica so would work. VMs using passthrough storage and virtual fibre channel aren't supported with Hyper-V Replica.