I really wish there was one, but believe me, I have looked! I'm about to set up a Windows 7 virtual machine on my main computer, so I can run the 2007 OneNote, that doesn't use other people's computers for storage.
@Richard_Littler obsidian, although your ability to drag things around is limited. (put the text in one file, then put that file on a canvas.)
edit: strictly speaking not open source, but it's free and they seem enshitification-resistant. and if they go evil your data is just in normal images and text files on your hard disk; you're fine.