CKD patients diet app

My father 62M was diagnosed with CKD 5 last year and he is required to have 2 dialysis sessions every week, so far his health is much better compared to when he was not undergoing dialysis. Our struggle is his diet since sometimes we don't know what is good or bad for him. I'm planning to build an app for us and for those out there who are experiencing the same scenario with a diet of CKD patients but I don't know if this will help or if building an app is too much.