@tlucia
If you have access to a mobile hotspot, you can setup your Roku Express using the hotspot. After successfully setting up and activating, you can then go to Settings/System/About in the Roku menu and see your wireless MAC address.
You can do similarly if you have access to another network (friend,family, etc.). Setup your Roku on this alternate network and then view the wireless MAC address in the Settings.
Roku Community Streaming Expert
Just another Roku user... I am not a Roku employee.
Insignia RokuTV, Ultra 4660, Premiere+ 3921, Express 4k+ 3941, Streambar 9102