It's only because FreeBSD is my desktop OS, and so I used kqueue during dev. I understand that there's a compatibility shim for Linux, so theoretically a port should be quite easy. The bulk of the code is in Rust, and that shouldn't need porting at all.
The note-taking app seems more like a proof of concept than any kind of category-killer, though.
I'll be keeping an eye on that protocol, though.