I was hoping the Muslim pro team could work on adding the three white days in the lunar calendar. The app could possibly tag these days just like it marks other holidays or like adding custom birthdays of yourself and friends. A reminder could then be setup with a hadith of the significance etc.
Another idea is to possibly integrate with Google calendar and others but I understand that it may be out of scope.
The article below describes the significance of these days:
May Allah swt put barakah in all your efforts and accept it from you.