I want to make Naan, but I am on the Keto diet and traditional wheat flour has too many carbohydrates. Can I make it with vital wheat gluten instead of flour? Do I have to add anything else? 
"High" gluten flour has, at most 15% gluten. "Indian" white flour, or maida has 7.5%. If you manage to pull it off, you basically end up with what's essentially a pan fried slab of mock meat, rather than a bread - basically seitan. You typically add gluten to flour to modify its characteristics - the only way you're going to be able to make naan that approximates a real naan in any way is, well, adding flour. 