Based on what you've said, you really should give org-mode a shot. (And org doesn't even have to be text only!) Given that word-wrapping is a priority for you,

Based on what you've said, you really should give org-mode a shot. (And org doesn't even have to be text only!) Given that word-wrapping is a priority for you, be sure to turn on org-indent mode and visual line mode. This gives you traditional outliner formatting with the indentation you'd traditionally expect (similar to how OneNote indents blocks) and proper word-wrapping. Although org has a huge ecosystem (org-roam is quite good), you don't need to go beyond plain org-mode if all you want is the features and general working model of OneNote. It's basically all there, batteries included.