Not a single photo of the palmfrets in the article, wow. Closest you get is a hand covering the entire device.
I was much more interested once I saw the actual website.
Long story short, it's basically a fret at the bridge end of the guitar, so using it will bring the 'root' note of the bass strings up a semitone or few.
I can see this being pretty useful for drones when fingerpicking. Though combining this with normal frets on the top string will necessarily be inaccurate because it shortens the string length, so the normal frets will be slightly misplaced.
The angle of the wrist on the front page makes me wonder about RSI.
Then the article did its job, driving you to the actual website.
Yeah — I don't really see how it can work except on the bass strings (played open).
This is a novel but slightly peculiar take on this problem. But there are lots of other things, right?
Listing for others since I suspect you know: all of this scheming about live-manipulating the basic tuning of an electric guitar dates back to the Parsons-White stringbender (and arguably further, since that was a way to get pedal steel sounds), which has led to stuff like the Duesenberg Multibender, the really extraordinary MayTrem (which keeps all strings in relative tune as the pitch is bent), the amazing Hipshot Doubleshot which lets you tune a guitar or dobro in two separate open tunings and switch between them instantaneously with a lever, etc.
Ed Gerhard added single-string frets to the bass side of his weissenborn (acoustic lap steel) that he can play with the fingers behind his slide or (incredibly) with his thumb.
All of these things are sort of fiddling at the edge of the question of a musical instrument, which is: should you confound their constraints or work within them? It's a bit like the thing about whether a dulcimer should be diatonic, whether you should add just the frets you need, whether it should be chromatic, whether it should have removable frets, etc. etc.
As a sort of hobbyist lap steel player I find all these things fascinating, but I think the ultimate question is — where do you draw the line? There are lots of things I can't play on a six-string lap steel, but should I change the instrument so I can, or should I accept the role the instrument plays, and play the things I can?
Another way to look at it is: why is the Harpejji niche? Why isn't everyone playing the Linnstrument? Why don't all pianists play the ROLI Seaboard?