Script must only be given signed device drivers. Some scripts will allow overriding this requirement through #osinfo_install_config_set_driver_signing function. You can query if a script supports this by checking if #OSINFO_INSTALL_CONFIG_PROP_DRIVER_SIGNING configuration parameter is used by the script in question (or other scripts in the same profile).
A warning will be issued by OS installer if device drivers are not signed and most probably require user input (and thus breaking unattended installation). See #OSINFO_DEVICE_DRIVER_SIGNING_REQ_STRICT on how this warning can be disabled for some scripts.
Script do not require device drivers to be signed.