Getting "favourites" (stored locations) on and off the Garmin Drive navi is slightly more fiddly than it needs to be, but doesn't require Windows even slightly. Here's what worked for me.
I have recently purchased a Garmin DriveSmart navigation unit. It is quite possible to get this up and running, legally, without buying a copy of Windows or Mac OS. Here's how. I believe this will also work with DriveAware and DriveLuxe models.