I recognise the recipe for this.
It will be as low as they say and it will be a large loaf with very large slices and it will taste pretty good.
It is basically the "Best Keto Loaf Ever" recipe which can be found on the Keto King Youtube channel and which I've shared here in various places but this has had preservatives and palm oil and rapeseed oil added - presumably to reduce the tendency for this loaf to go mouldy if you keep it in a plastic bag. I keep my home made ones wrapped in cloth to avoid this.
The vital wheat gluten is the gluten part of the wheat which is almost 100% protein and has minimal carbs - the rest of the recipe is mostly fibres and the wheat flour references are to baking powder which contains traces of wheat which won't affect carb content but will affect people with a wheat allergy so they have to put it in heavy type and the flour conditioner - not sure what that is - might be another dose of vital wheat gluten which is what it is usually used for - sometimes producers mention the same ingredient twice if they use it for different purposes.
But yes - I would say this is bona fide and the values stack up. In a commercial environment they will be able to get the loaf to puff up more and so get more slices out of each loaf which reduces the carb per slice down. My recipe is 1.6g Carb per slice but I use different ingredients.
I personally wouldn't buy anything with rapeseed oil nor palm oil but that is down to personal choice.
Here's the youtube if anyone wants to make their own: