To expand on this, it is really hard to even get data sheets on e-Ink unless you have serious cash and are going to order tens of thousands of units. Unlike LC

To expand on this, it is really hard to even get data sheets on e-Ink unless you have serious cash and are going to order tens of thousands of units. Unlike LCDs, e-Ink has complicated voltage waveform requirements. The voltage waveforms are what allow partial refreshes and all the other unique benefits of eink - and they are all proprietary. And there aren’t multiple competing manufacturers, so even though some of the key patents have expired we have not seen a renaissance of display modules. The situation has actually gotten better - there are a few modules available now for tinkerers from Pimoroni, Waveshare, and AliExpress. But when LCD modules cost 1/10 the price (particularly for larger displays) it becomes hard to justify e-ink. The largest untapped market for eink is replacing segmented LCD displays for many products. They did not make many inroads because the costs were higher and LCD segmented displays are commodities that even amateurs can order prototypes of for less than $100 with standardized connectors and controllers. E-ink displays were thus only pushed for by aesthetic reasons by product designers.