Of the boards examined, six of them have OLED displays, but one has an E-paper display. To summarize results, [Andreas] summarized his findings on these seven along with others in an online ...

In addition to the Pico D4, the board sports a USB charging and programming socket, a low drop-out (LDO) voltage regulator, an accelerometer, a tiny RGB LED, and a 96×16 OLED display.

As Hackaday revealed, this one comes with an E Ink display, a secondary OLED panel, and a keypad made of soft silicon that is encased within a see-through case.