Quite digestible, but you have to cook it far longer, about 5–8 hours. There is a dish called Haleem that is popular in the middle east, but each country and region has their own version of it [0]. The version I am familiar with is served as breakfast food, similar to porridge. Its main component is wheat cooked overnight over low heat. Although it should be noted that it is made with wheat endosperm, not whole wheat. But buying one is no more difficult than the other.

[0] https://en.wikipedia.org/wiki/Haleem