The primary reason coconut flour recipes (especially a high hydration recipe like pancakes) end up tasting like eggs is because they are primarily eggs with very little flour.
Coconut flour is extremely absorbent, which means two things:
For the same amount of liquid, you need less coconut flour compared to other flours like flaxseed meal, almond flour, etc. Because you must use less of it, there is less flour "flavor" that comes through to the final product, if that makes sense.
For the same amount of coconut flour compared to other flours, you need more liquid. Because coconut flour has very little protein compared to other flours, that liquid tends to be eggs, which have the necessary protein to provide structure.
Take a muffin recipe for example (I've omitted all other ingredients besides flour and eggs for sake of clarity).
Flaxseed meal version:
- ¼ cup flaxseed meal (28 g)
- 1 jumbo egg (63 g)
Coconut flour version:
- 2 Tbsp coconut flour (14 g)
- 1 ½ jumbo eggs (95 g)
Now let's look at the baker's percentages of eggs to flour in both of these recipes. In the flaxseed meal version, we see that the weight of the egg is 225% compared to the flour (if the flour were considered 100%). In the coconut flour version, the weight of the eggs are 642% compared to the flour.
Something that uses 642% eggs is likely going to taste a lot like eggs. But wait, we're not done yet. Most pancakes recipes are simply flat griddle-cooked muffins, though they tend to have even more liquid than regular muffins. That likely means even more eggs, and egg ratios upwards of 800-900%. At those levels, it's more like an omelette with the coconut flour just going along for the ride.
Whether you can substitute vital wheat gluten (VWG) in place of eggs is really going to depend on the rest of the recipe. Without knowing what the other ingredients are, it's hard to make suggestions. If eggs are the only ingredient providing moisture, then substituting with VWG alone won't work without also adding a source of moisture.
My gut feeling is that VWG would tend to exacerbate the requirement for moisture (it's also very thirsty), and tend to make leathery pancakes. Actually, I suppose it might theoretically be possible to replace the function of an egg by combining a small amount of vital wheat gluten (say, 6 g) with a non-egg source of liquid like buttermilk (say, 45 g). I'll have to try experimenting with that and report back. Until then, this is how I approached solving the "eggyness" problem:
EDIT: since posting this, I've developed a coconut-flour version of my low-carb
Buttermilk Pancakes #12 recipe, which I'll include here. While I know this isn't a recipe exchange site, I think this recipe can help show how I approached solving the OP's original problem of too much "eggyness":
Buttermilk Pancakes #12 (Coconut Flour + Whey Protein Isolate)
3 ½ Tbsp coconut flour (*flour*) 42.98% 24.5 g
1 Tbsp psyllium husk powder (*flour*) 14.91% 8.5 g
¼ cup, packed, unflavored whey protein isolate (*flour*) 42.11% 24.0 g
¼ tsp baking powder 2.02% 1.2 g
1/16 tsp baking soda 0.51% 0.3 g
1 Tbsp Splenda (non-nutritive sweetener) 2.96% 1.7 g
3/8 tsp Kosher salt 1.84% 1.0 g
1 jumbo egg 110.53% 63.0 g
1 cup buttermilk 429.82% 245.0 g
1 Tbsp unsalted butter 24.86% 14.2 g
A couple of things I'll note. First, this recipe has around 475% hydration, so it's still quite high, but it solves the eggyness problem by using only 1 egg. To make up for the structure and liquid that the egg would normally provide, I replaced it with several ingredients which work together to function like an egg. First is the unflavored whey protein powder. When mixed with the buttermilk and cooked, it will set up similar to how an egg might set up. However, being a pure protein powder, it is an extreme "drier" (similar to egg whites), and would produce an inedible dense pancake by itself. To balance that out, I added a moisture retainer in the form of ground psyllium husk. The psyllium husk also acts like a binder and holds everything together similar to how an egg might. The end result is probably the equivalent to around 3 eggs or so without tasting like an egg.
P.S. I originally posted this recipe along with 3 other low-carb flour variations over on reddit.
Regarding the carbs in buttermilk (and yogurt): While the nutrition info for 1 cup (245 g) of buttermilk and 1 cup (245 g) of whole plain (unsweetened) yogurt will say around 12 g of carbs from sugars, in reality, that number is actually much lower. The reason for this is that most of the milk sugar (lactose) in buttermilk and yogurt has been converted by the bacteria culture to lactic acid. As doctors Jack Goldberg and Karen O'Mara explain in their book "The GO-Diet", you can count a cup of either of these as 4 g of net carbs rather than 12 g. (See this website for more info: http://www.lowcarbluxury.com/yogurt.html).