The Smart Boy is part of a new breed of April Fools' jokes that double as market testing. They're jokes! Unless you really like them, in which case they're marketing!
This particular concept art, published on accessory manufacturer Hyperkin's Facebook page on March 31st, was described as upcoming hardware that will clip onto an iPhone 6 Plus (and eventually other smartphones), and play Game Boy and Game Boy Color cartridges on the screen. The design scanned as a joke, looking like someone cut loose the lower half of the classic Nintendo portable and molded what remained around an iPhone.
But on April 1st, Hyperkin posted a second update:
"A lot of you were speculating that the Smart Boy is an April Fools' Joke. Well, it sort of was....