In the section: OS with a Security focus (Complete Cyber… Vol1), you recomend Debian as OS.
Is ok to run Debian in av VirtualBox on W10 or should it be a Clean install?
It is recommended to use any virtualization technology rather than going for a clean install or even dual boot. You can use a virtual box or VMware. You can read here whether to go for VirtualBox or VMware https://www.nakivo.com/blog/vmware-vs-virtual-box-comprehensive-comparison/