Yes, it depends on VirtualBox. But there are versions for KVM, and for Qubes. More of a nonstarter, though. Or even using physical devices, such as Raspberry or Banana Pi.
Years ago, I created a LiveDVD with VirtualBox plus Whonix gateway and workstation VMs. I had to hack at both Whonix VMs to reduce size and RAM requirements. But I got a LiveDVD that would run with 8GB RAM. It took maybe 20 minutes to boot, but was quite responsive.
Edit: I forget that I'm writing on HN. When I say VM, I'm referring to full OS-level VMs, not namespace, Java, etc VMs.