As a Mac and Windows user I've never used google keep as there is no native app.
Evernote native vs web Sublime Text vs Atom Mail Client vs Web mail etc.
Google Keep works offline, it has seamless syncing when it is online and I can access it from all my devices (including my phone).
I guess you don't consider a Chrome App to be a "real" native app and that somehow makes it different for you, but I don't see any meaningful distinction.
Not native, but feels close enough for this type of thing to me.