Welcome Dave! :waving: Yes, please do post a link or pictures of your engravings on glass. Yes, I'd think anything you're now doing with a rotary on glass you could use the same technique on metal. If you purchase a graver later you could combine the rotary with a graver for your art.
If using the rotary on metal the first think you'll notice is the metal can burr up and glass won't. The carbide rotary burrs can be more aggressive in metal than what diamond burrs are.
Steve