Re. native part -- I recently explored JavaFX for desktop, and found it's actually very fast, both to run and to develop in. I'd say it's a joy to use, don't understand why market now prefers other heavy-weight solutions like Electron. Maybe it was released at a wrong time, when Sun Microsystems had troubles? Maybe it was too early? Or maybe a ton of software is being written in it without fanfares, I dunno.<p>The whole binding stuff is neat, feels like a predecessor to Reactive Streams (which is itself is already standardized in Java under java.util.concurrent).
Let's see how it goes, still searching for a good FM on mac. Regarding full-featured file managers on OSX - there's Double Commander. Works well, preview on F3 is fast (and can use system preview for various media files). A bit unstable though, and behaves weird on network operations.