Virtual servers (as opposed to hardware workstations or servers) will usually have their “KVM” build in to the hypervisor control plane. ESXi, Proxmox (KVM), XCP-ng/Citrix XenServer (Xen), Nutanix (KVM-like), and many others all provide access to this. It all comes down to what’s configured on the device.

VMs are easy because the video and control feeds are software constructs so you can just hook into what’s already there. Hardware (especially workstations) are harder because you don’t always have a chip on the motherboard that can tap that data. Servers usually have a dedicated co-computer soldered onto the motherboard to do this, but if there’s nothing nailed down to do it, your remote access is limited to what you can plug in.