I see a lot of vxdiag vcx nano for sale different colour and for different manufacturers.
Is the hardware all the same? So I could buy one and use with ford, vag, Toyota etc or are they different for each manufacturer and have to buy individually?
All vcx nano firmware is different. They are single car brand devices. You should purchase different hardware for different manufacturers.
The one with white color case supports USB connection only. The blue case one supports both USB and WiFi connection (has WiFi component inside).
If you want to enable more than 2 license to vcx, you can choose vcx nano pro or vcx plus.