Ask HN: Are there any good open-source OneNote alternatives?

I use OneNote to make notes on and organize whatever I'm reading. But I would prefer to use an open source alternative(which I could self-host). Also, I sometimes have a sync issues with OneNote, making it difficult to rely on. Any ideas?

A pure markdown based solution isn't really ideal. I like the rich text formatting of OneNote and the ability to insert media, draw over it, etc.