The Equinix Metal SOS/OOB works by using SSH as an authentication mux and transport medium for connecting a Metal platform user to a virtual serial port that is redirected to by the chassis underlying lifecycle controller (iDRAc, IPMI, iLO etc), and it's great.
There is a painful limitation that it requires that correct serial port settings to be configured by the customer's side, and access is limited to things that can be rendered by serial I/O.
Modern lifecycle controllers, (iDRAC and IPMI specifically), also expose a VNC server that exposes traditional keyboard, video and mouse control to the guest OS. Having access to a KVM driven by VNC would open up a number of operator workflows that are currently impossible or out of reach.
The idea here is to take the current SSH authentication / mux and extend it with a port redirection, where that port redirection includes a VNC framebuffer going by to the iDRAC/IPMI hosted VNC endpoint, allowing direct control of the iDRAC/IPMI KVM via VNC from the end user, wrapped in an SSH channel.