Is aquafaba readily digestible?
Much of it is not readily digestible. According to this chemical analysis:


  Finally the results presented here also indicate that the amount of digestible carbohydrates in aquafaba is minimal. For families with GLUT1 deficiency, where a diet with minimal amounts of glucose and carbohydrates digestible to glucose is required, aquafaba can represent an additional foaming or emulsifying ingredient, as an alternative to eggs.


It also contains proteins, presumably digestible. The carb and protein content is significant, according to the study, which implies a fairly decent proportion of undigestable carbs.