This is a good time to switch to Notesnook, which has a OneNote importer.

Why am I about to shill so hard for this particular app? Simple, because after Evernote enshittified over a decade ago, I switched to OneNote as the least terrible alternative, and then spent the next ten years trying to find an actually good, open source notes app.

Call me Ahab because this motherfucker has been my white whale for a not-insignificant portion of my life.

Notesnook, finally, hit everything I wanted;

• You can self host it (but you don't have to)
• Self hosters get everything on the paid plan for free
• It has a web app, a desktop app, and a healthy ecosystem of phone apps, with - very importantly - 1:1 feature parity. Everything you want to do you can do from any of the interfaces and for the most part they're even laid out identically.
• It has a proper rich text WYSIWYG editor. It does not demand you learn FUCKING MARKDOWN. JESUS H CHRIST I DO NOT WANT TO LEARN A FUCKING SYNTAX TO MAKE NOTES, WHAT IS WRONG WITH YOU?
• But for those who care about that stuff, it is built on markdown, and all your notes can be exported in markdown, so there's no lock in. And you can use markdown in the editor (without even having to switch modes like a lot of other editors).
• Everything is encrypted by default. Notes can also be individually password protected.
• You can share copies of notes with optional password protection and self-destruction.
• It has a really slick UI. Everything works, everything is intuitive, there are tonnes of keyboard shortcuts. I find I actually have an easier time writing long form text content (such as a novella I'm working on) in Notesnook than I did in Word or LibreOffice.
• It builds a TOC for notes automatically. You can link notes to each other, and links are bidirectional so you can track which notes link to a particular note.
• You have sorting by both tags, and notebooks. Notebooks are infinitely nestable, and - this is really cool - notes can exist in multiple notebooks simultaneously.
• It has robust web clipper for Firefox and Chrome.
• Very robust attachment support.
• God so much more, I'm having to deliberately stop here.

What it's currently lacking is drawing support. If that's a must have for you, check out Joplin instead (at least for now, I've seen some talk about Notesnook integrating Excalibur for digital canvas, which would be a superb solution).

Anyway, please check out Notesnook. It's excellent, and I like sharing excellent things. https://notesnook.com/downloads/