Non-profit, open source and extremely privacy consious. You'll need a rooted Pixel device and you can download/learn about the ROM here: https://grapheneos.org/
I liked GrapheneOS but I didn't like the pixel hardware personally
I would echo what OP said there, I had to get a temporary replacement phone while my main one was getting a screen repair, and I was amazed at how good a Galaxy A was for the price. Think it was about ÂŁ120 or so, and it's a great phone.