Para contar con una respuesta oficial, después de buscar exhaustivamente encontré lo siguiente:
VMware vSphere Hypervisor
VMware vSphere Hypervisor is a free product that provides a simple and easy way to get started with virtualization at no cost. vSphere Hypervisor provides only basic virtualization capabilities, allowing customers to virtualize servers and run applications in virtual machines in a matter of minutes. vSphere Hypervisor cannot connect to vCenter Server and therefore cannot be centrally managed. Users can remotely manage individual vSphere Hypervisor hosts using the vSphere Client. There are no restrictions on the number of cores per physical CPU, on the number of physical CPUs per host and on the amount of RAM per server/ host. The maximum vCPUs per virtual machine is eight.
Documento oficial y actualizado a la fecha.
VMWARE vSPHERE AND vSPHERE WITH OPERATIONS MANAGEMENT Licensing, Pricing and Packaging
En este vídeo se especifican algunas de las limitaciones de hardware:
Diríjase al enlace vSphere Hypervisor: descripción general de las licencias
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VMware vSphere Hypervisor gratuito, virtualización gratuita (ESXi)
Espero haber podido ayudar.
Saludos,