This video talks about running macOS inside Linux VM.

I was not able to install the recommended Manjaro Linux on Hyper-V in Windows 10 Pro. While booting from the ISO image there was an error about the graphics card.

Instead Gentoo I used Ubuntu 20.04.1

I also had to use PowerShell to expose the virtualization extensions on the Ubuntu VM:

Set-VMProcessor -VMName "Ubuntu 20.04.1" -ExposeVirtualizationExtensions $true

To enable nested virtualization in Oracle VirtualBox:

cd C:\Program Files\Oracle\VirtualBox
VBoxManage modifyvm ubuntu2004 --nested-hw-virt on
bcdedit /set hypervisorlaunchtype off   - this disables the auto launch of the hypervisor.

To enable it again:

bcdedit /set hypervisorlaunchtype auto