Found on Cycle Trader, but no mention of the origin or manufacturer.
Dave, I don't recognize the product, but it looks nicely made, whether somebody's homebrew or a commercial product.
If no one can help you out in identifying the product, and you're interested in an equivalent DIY project, it's certainly doable. I fabricated something like that myself, when I had a Victory bagger ('12 - '17):
That's a threaded 15mm rod, with some screw-in end bolts, and some hardware store brackets (two of which are held in place courtesy of existing screws that hold the windscreen on).
In case you're not familiar with this, 15mm rods are a de facto standard in the world of photography. That size rod is used for assorted tripod-related extensions, mounting extensions for all sort of photo-related doodads, and so forth. Hence, to go along with the rods, you can buy all sorts of clever adjustable mounts, such as the double-angle gizmo and short rod I mostly used in that setup:
In a somewhat similar fashion, I used some RAM products to put a bar up like that on one of my former Burgman scooters that I had after that:
That particular RAM product used, as I recall, a ½" rod, which was merely for an extension, not for mounting anything on it. I drilled out those end holders to accommodate a (slightly larger) 15mm rod I had lying around, and pretty much duplicated that earlier setup. (Of course, this particular setup was dependent on my already having some replacement brake-reservoir covers -- which had standard B-size RAM balls incorporated -- made by a company that is no longer in business.)
My point here is that with some creativity, you can essentially duplicate that setup you pictured. And if you do so, I recommend that you go with something that incorporates a 15mm (OD) rod.
If I do come across the pictured mount, I'll be sure to let you know.
Oh, and by the way, I'm still, um, focused on your question in terms of a GPS (or maybe phone) holder. If anyone's interested, using those bars for a camera mount was just sort of an experiment. I have long since abandoned that idea, and for the last half a dozen or so years gone with a suction-cup mount on the front of bike windscreens (well, except one bike that doesn't have a windscreen). Mounting way up front with a suction cup eliminates reflections, increases light (if behind a tinted windscreen), and it's easier to keep the one-square-inch of a GoPro lens cover squeaky clean than it is to clean an entire windscreen.