Quote https://github.com/QubesOS/qubes-core-admin-addon-whonix:
/etc/qubes/post-install.d (with .sh extension), with just one call:
qvm-features-request whonix-ws=1
inquiry:
https://github.com/QubesOS/qubes-issues/issues/3765#issuecomment-386805491
add anon-vm tag to whonix-ws-based VMs
https://github.com/QubesOS/qubes-issues/issues/3595
TODO (release critical blocker):
https://github.com/QubesOS/qubes-issues/issues/3951