main thing to note is that NFS is an object based storage (acts like a share) where iSCSI is block based (acts like a disk). You’d really only use iSCSI for things like VM disks, 1:1 storage, etc. For home use cases unless you’re selfhosting (and probably even then) you’re likely gonna be better off with NFS.
if you were to do iSCSI I would recommend its own VLAN. NFS technically should be isolated too, but I currently run NFS over my main VLAN, so do what ya gotta do