VBoxHardenedLoader

Hello developers. Question - is VBoxHardenedLoader compatible with Whonix?

VBoxHardenedLoader is completely incompatible with Whonix, any change in accordance with the instructions will violate anonymity.
VBoxHardenedLoader is fully compatible with Whonix, any change in accordance with the instructions is possible, anonymity will not be violated.
VBoxHardenedLoader is partially compatible with Whonix, if you make only some changes, other changes in accordance with the instructions will violate anonymity.

Thanks in advance for the reply.

I highly recommend you do not use it.
if Virtualbox does not provide you sufficient protection, you should look at other hypervisors, or you could run Qubes-Whonix.