The most common modern geometry is the fourth one ("LCD") in your second link, where each pixel is indeed perfectly square. That's what I was referring to.

The fact it is made of three rectangular subpixels in no way means "pixels can't be square".

And the "glowing" effect in your picture is an artifact of light bleed from your camera. The only time we perceive pixels as round rather than square is if we have eyesight problems that blur the image projected onto our retina.