Would you say it could be possible to code with such display if it was attached to a laptop?

I have an old Acer Aspire One netbook which I modded with a Pixel Qi display. It is definitely usable for programming in direct sunlight, though the display is physically too small to get comfortable doing a lot of programming on it. Funnily enough, the major problem is not enough sunlight -- indoors, you can use the backlight, and direct sun provides a good contrast ratio outside, but in the shade outdoors, particularly after my eyes have adjusted for sunlight, the screen becomes difficult to see.

Hmm, I see. Did you have problems to adjust to other normal screens too, or it was just with that Pixel Qi one?

Just the Pixel Qi. In indirect light, the contrast ratio is much lower than, say, a Kindle, which is itself much lower than paper. So unless the sun is directly on it, it's harder for sun-adjusted eyes to read than a Kindle, or than it is for indoors-adjusted eyes to read a normal backlit LCD.