Disable "secure-boot" for EFI boxes
This allows Boxes to boot EFI systems even when secure-boot is not supported by the environment.
This uses the newly introduced libvirt-glib gvir_config_domain_os_enable_firmware_feature
API.
https://gitlab.com/libvirt/libvirt-glib/-/commit/a6db3f314510b4
With this, users should be able to run GNOME OS and (soon) other EFI-only systems in the distro-packaged version of Boxes of their choice.
While the Flatpak version of Boxes currently handles well secure-boot, distros have not. Just a few distros support EFI and provide the proper environment for the virt stack that Boxes needs to boot EFI VMs consistently.
The distro-packaged version of Boxes runs without the constrains of the Flatpak sandbox, and can provide additional (useful) features such as USB redirection, Network Bridge, etc...