A reading journal
Keep the passages worth keeping, and what they argued with in you. Part commonplace book, part record of who you were when you read it. The margin notes, gathered in one place.
Part of Innerholm+. $40 a year, or $5 a month. The free editions stay free because Plus pays for them.
No ads. No trackers. Nothing trains on what you write. Search across years, sync between your devices, and export everything as Markdown, Day One, or PDF whenever you like. How privacy works.