Someone recently asked after checking this podcast "But what and how do USB fall into that, I got a HDD over USB".

In the podcast I only went over the physical HDD directly connected via SCSI or ATA but it's mostly the same for other inputs.
On Linux it uses the LIO: https://en.wikipedia.org/wiki/LIO_(SCSI_target)

All those devices are called SCSI initiator/target: https://en.wikipedia.org/wiki/SCSI_initiator_and_target

What you can understand from this is that there's a new layer of translation.