Colour e-ink is available for retail purchase, and the colour reproduction is passable.

The refresh time is big fractions of a minute, but that's OK for static displays.

Obviously that misses the entire point of this parasiteware, which is advertising and tracking.

That's a good point, and tbh I was aware of color e-ink but I assumed the price difference was enough to be a non-starter for a (parasiteware) company.