Connect to the console (Serial or SSH) and select option 12 (Developer Shell) or 8 (Shell). Run the following command to query the hardware BIOS: 360 Portable - Autodesk Fusion
From the Shell (Option 8): Rns 510 Maps Tool V3.0.7 Download Better Site
When managing a pfSense firewall, the "serial number" can refer to two different things: the hardware serial number (relevant for appliances like Netgate SG-1100, SG-3100, etc.) or the software license serial number (relevant for pfSense Plus).
sysctl -a | grep netgate (This often reveals the specific Netgate device ID and hardware serial).