Yes, non-nested or flat structure is supported in Cuckoo Sandbox. To set up a non-nested configuration, you can configure Cuckoo Sandbox to use VirtualBox as its VM platform and then configure VirtualBox to use a separate VM for the guest machine. This configuration will allow Cuckoo Sandbox to monitor and analyze the traffic and behavior of the guest machine without running it inside of the Cuckoo VM. You can find more information on how to set up a non-nested configuration in the Cuckoo Sandbox documentation.