does an on demand HWT in the garage need to be pluged into a GFCI outlet on a dedicated circuit?
What is a HWT? What is the voltage?
I don’t know of any current exception to having GFCIs for garage receptacles (excluding the one for the door opener in the ceiling).
The on demand water heater would be required to be hard wired in armored cable in this area, but it would not be required to be GFCI protected anymore than any other water heater.