I think the process of its installation is a bit completed running the two same operating systems on one machine.
But there isn’t an article about how to install macOS Big Sur on VirtualBox on Mac. There are lots of articles about how to install Windows 10 on Mac using Boot Camp. Although, there are Virtual machines such as VMware Workstation/ VMware Player, VMware Fusion, VirtualBox, that offers you the best installation environment on it. In previous articles, we explore the ways of installing macOS Mojave 10.14, macOS Catalina 10.15, macOS Big Sur 11.0 on Virtual Machines.