finally, i did it.
as i’m using secure boot, i follow the “hack” on GitHub - CheariX/silverblue-akmods-keys: Fedora Silverblue with SecureBoot enabled and working akmods such as akmod-nvidia or akmod-VirtualBox. for signing the binary blob with my own certificate.
i injected
echo "%_with_kmod_nvidia_open 1" >> macros.kmodtool
just before running the provied setup script. There is no need to install akmod-nvidia-open-Package.
Cheers.