i use a cool little program called cherrytree[0]. i don't use it on my phone as i really don't use my phone, but i save the password-protected cherrytree data in dropbox and have cherrytree installed on my computers.
edit: to use it with android, it looks like this is the app for that [1]
It's funny how my own perceptions have changed over time. Maybe ten years ago, I would have looked at that and thought "careless user interface design". Nowadays, that very same thing somehow conveys trustworthiness to me.
edit: to use it with android, it looks like this is the app for that [1]
[0] https://www.giuspen.net/cherrytree/ [1] https://github.com/FFDA/SourCherry/