To enable Windows Sandbox in firmware, ensure your system supports virtualization. Access the BIOS or UEFI firmware at startup and enable the virtualization setting (Intel VT-x or AMD-V).

On Windows 11, you can use the "Windows Sandbox" feature to create an isolated lightweight virtual machine to test ...

Nested Virtualization lets you run a Hypervisor inside of a Virtual Machine. Windows 11/10 has introduced Nested Virtualization. Here is some information that might interest you.