I’d say, all the “remaining” areas - like edges, cracks, tiling imperfections - could be… just, you know, painted white high reflectance paint that’ll be soon covered in dust anyway? This whole technology looks like a few % optimization over widespread and long adopted “white buildings are cooler in hot environment” thing for hype and whitewashing. Sure it’s worth doing in punk DIY setups.

Not that I’d adopt that, I still live in cold climate, even with all the warming, I’m going to burn black all non-greenable and non-solarable surfaces black to get some extra heat energy locally.