Yeah, you can do it, but it’s tricky. With KVM/QEMU you can point the VM straight at the physical disk, like /dev/sdX. VirtualBox can do it too with a raw VMDK mapping.
Couple of warnings though: Windows doesn’t like being booted both natively and as a VM, you’ll hit driver conflicts and probably activation issues. And for Diablo IV, you’d need GPU passthrough or performance will be awful.
For simplicity and best performance, dual boot is still the most reliable.