To my knowledge, UEFI does sorta do hypervisor-y things when running a 16bit bootloader since the GPU needs to be operated from 64bit ( via it's UEFI driver) and keyboard and mouse need to be emulated via UEFI drivers, which are also 64bit. That is unless the device has a CSM module and can run natively 16bit code during CSM boot, which not all devices can do.