A Linux machine with libvirt and virt-manager installed.
Here’s a detailed, long-form post suitable for a tech blog, Reddit (r/networking, r/fortinet), or a community forum like the Fortinet Cookbook or Medium. Diving Deep into fortios.qcow2 : The Heart of Fortinet Virtualization fortios.qcow2
Disclaimer: Always verify your licensing. An unlicensed fortios.qcow2 will limit throughput to ~1 Mbps and will expire after 15 days. You need a VM01 or VM02 license from Fortinet for production use. A Linux machine with libvirt and virt-manager installed