Can you get a good bread by adding something like this in the mix(100g of it with 400g of whole wheat flour)?
You can add pretty much anything you want to eat to your bread. The only issue will be the lack of gluten development. Whole wheat flour has less gluten than bread flour already, plus it has the bran which can cut gluten strands. Adding in a non-gluten protein source will dilute the gluten even more. If you use a little math to figure out your percentage of gluten in the final "flour" mix (the WW flour plus the protein powder) and decide how much you want it to be (probably somewhere between 11% to 14%), you can make up the difference by adding some Vital Wheat Gluten. You will also want to adjust your hydration level, because the protein powder is going to absorb water at a different rate compared to flour. With these two considerations in mind, you can easily add that protein powder, and maybe even more if you wanted to. Tell us how it turns out!
We had this topic just a view weeks ago:
You can find my formula for this bread there, where almost half the flour was substituted by protein powder: