https://wccftech.com/apple-testing-e-ink-display-technology/

Apple’s foldable device range is yet to launch, and that could be because the company is testing various display technologies for it, including e-ink, according to a notable analyst.

The implementation of e-ink display technology could still be several years from now, but Ming-Chi Kuo claims in his latest tweet that Apple is testing it for foldable iPhones and foldable iPads. The California-based technology giant is likely testing out different foldable prototypes, where one of them includes a secondary display like the Galaxy Z Fold 3, also known as a cover display.