Comment OneNote (Score 2) 10
This sounds a lot like OneNote. Remember when OneNote was great?
Not that cloning OneNote-when-it-was-great is a bad thing, I'd really love to see a good 2010-ish OneNote that supported all the platforms I use, and let me store data (encrypted, of course) on the target of my choice (the usual suspects, Backblaze B2, pCloud, sync.com, etc.).
I'm currently using Obsidian.md with my notes stored on pCloud, but old OneNote had such a great UI for managing notebooks, folders, and notes. I used Joplin (with encrypted notes stored on some cloud) before that. Everyone seems to be cloning OneNote's current terrible "simplified" UI... I'm happy to type notes in Markdown, but I need better notebook/folder/note management, I guess.