Update: QEMU support is deprecated in favor of KVM. The slow performance of pure emulation makes it non practical for most of the Linux user base. The majority of consumer systems should support the hardware virtualization extensions required by KVM.
You can run Whonix with QEMU instead of VirtualBox or KVM as well. There is no specific documentation about QEMU, because instructions would be very similar to the instructions on Whonix's KVM wiki page. Instead of importing Whonix KVM Templates, you can simply import Whonix QEMU Templates.
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