I was considering Obsidian, and your comment worried me enough to investigate.

Looking through that link, though, I don't see anything too absurd. It's a closed-source app, which isn't ideal but is common enough. It looks like they have a Github repo that explicitly does not have the core source code but hosts some secondary files, and that's spelled out in the first couple lines of the readme.

Seems fine to me, overall. Maybe there's something objectionable I missed in there?