Pixy2 can detect an object that is miles away as long as the object is large enough. Described another way – Pixy2 will detect an object that's as small as 4×1 pixels in the image. This means it can detect a ping-pong ball sized object at 10 feet, aka a 40mm object at 3 meters.
Regarding minimum focal distance: Pixy2 will focus on objects as close as 5cm / 2 inches away from the lens. Closer than that, they start to get fuzzy.