CAN Bus: Nodes powered by different Potential Sources
Many CAN tranceivers are isolated, but if that is the case in your display remains to be seem. If the display has no other exposed metal parts, then it is most like inherently isolated due to using any double isolated ac/dc power supply.
For example, any Kvaser interface is isolated. As you can recognize on the isolation gap on their PCB.

Also many devices using CAN bus have isolation if they are sold separately.
This is typical, but not required by the standard.
The reason for this is that it adds cost that you don't need. In a car, where everything is powered from the same battery, isolation has no benefit.
In large industrial machine where there can be many ac/dc converters or even generators, isolation makes the grounding (CAN_GND) easier.
Even though CAN is differential, it is not balanced. It still requires CAN_GND to keep common mode voltage in check. In a car this is just negative battery terminal and chassis. On mains it can be mains earth, with risk of ground loop. So you add isolation to break the ground loops.
Do you need to isolate your display? Read the manual, or measure ohms from CAN_GND to mains earth/dc-in.