Thanks for the information.
As for your "device", has it been and labeled as UL approved?
That is the first thing that comes to mind.
The NEC does not nor has ever governed any piece of equipment, appliance or apparatus.
Equipment is approved by UL and when done so, it has already met the requirements that are associated in its UL category.
NEC covers wiring installations in all aspects of buildings and its surroundings.
No different than a light fixture or dishwasher etc. NEC has no ruling on these items.
They only rule on the permanent wiring of the structure to allow connection of the items
So, in your case, it appears there is no relation to the NEC, only UL.
As far as NEC on grounds, if it has metal of any type, grounding is required.
If there is no metal, then a ground cannot be established nor required.
But that pertains to the electrical system of the building and each part has a different article in the code.
Grounding is covered in 100+ locations as it pertains to each part of the electrical system of the building.
As an example, look at all the lamps, radios and other electrical appliances purchased. Most have no ground because of the UL approval.
They work with the appliances , not the NEC
Hope that helps, just reply for clarification ot other information.