Looks like going into the UEFI screen you can change the boot order from SSD only (The Default) to
USB - SSD,
Network, USB, SSD
USB, Network, SSD
Network, SSD
Selecting one of those with secure boot enabled would look for Secure Boot files on the alternate locations before Booting to the SSD.
I suspect that if you use the Advanced Device Security and disabled Network Boot or USB then it would override booting from the device in the Alternate order.
Obviously you then need to enable the Administrator Password to protect your configuration.