There's no real reason why they couldn't make the product, it just seems highly unlikely that they're fully aware of the level of small scale integration needed to make it work.
Using a bright RGB LED and ultra tiny LCD panel would work but you'd need a pretty high resolution LCD to counteract the parallax without it looking pixelated. A special lens block would be better, to correct the image optically, but adds physical size.
A micro laser projector module would produce a great image at that range but is a little big for that size device, both in terms of physical size and available battery capacity.
It's also way out of their product price range.
And, their demo shows multiple colors, an RGB laser projector would be even bigger and more expensive.