Fgt-vm64-kvm-v7.2.1.f-build1254-fortinet.out.kvm.qcow2
You can deploy the image using the Virtual Machine Manager (GUI) or the command line. Create New VM: Select "Import existing disk image." Select Path: Browse to your .qcow2 file.
Filename breakdown and what it is
Set the correct machine type:
virt-install --machine q35 ...