Final answer:
The 'glimmers of firefly light' represent the glow from television screens inside homes in 'The Pedestrian', highlighting the dominance of technology in people's lives.
Step-by-step explanation:
The "glimmers of firefly light" within the house Mead passes in "The Pedestrian" are caused by the flickering of television screens. This is used metaphorically by Ray Bradbury to represent the pervasive influence of technology and how it has taken over the leisure time of the inhabitants, leading them to be indoors and disengaged from the outside world.
The effect is likened to fireflies because it is the only sign of life in the otherwise dark and deserted streets, much like fireflies would be the only light source in a natural setting at night.