[PikachuEXE]

For private notes & random images/files app I would suggest trying

https://joplinapp.org

But I use as private notes mainly, so can't say much on file storage side.

Multiple sync target (e.g. Dropbox, Nextcloud, OneDrive etc.) with E2EE.

But it's not polished so expect there might some strange limitations.

[l8rlump]

I'd like to try this but it seems that there are limited options to import from Onenote. As far as I can tell, you can either try converting to markdown with an older version of Evernote (IIRC with limitations such as text formatting being lost), or use one of a few users' hacky solutions involving Pandoc. Is there an easier/better way?

[PikachuEXE]

Sorry I have no idea

I started using it after Evernote with very few notes