I have a _terrible_ memory and am constantly forgetting things about friends I have known for almost a decade. I host this in a container that I am likely going to move to a RPi: https://github.com/monicahq/monica
I'll be honest - since I host it in a Docker container on my main desktop PC, I rarely rely on mobile, so I can't really say. I don't fill _everything_ in on Monica, I just try to hit the high-level items (e.g. they mentioned X, I should get them Y, etc.).
Monica really needs some sort of smart insertion system - just a free-form field that can parse a full sentence and handle the logistics.
For example, "Mary and I spoke on the phone last week and said she was going to Italy for a vacation and offered to show me photos" - Monica should be able to parse the conversation, the event and a follow-up somehow.