Without initial configuration, devices connected to LAN ports don’t have access to the Internet.
And initial configuration is possible only from LAN ports, not from the Internet (WAN port).
If you want to be sure, that your Omnia is safe, you can use 3 LED rescue mode (press RESET button and release it when 3 LEDs are shining) and your Omnia will be in factory reset mode (like after unboxing).
You can find details in documentation: Omnia - Turris Documentation.