The e-ink review say the display has a dark purple color. How is your experience?
https://i.imgur.com/kmKiqbO.jpg
You can zoom in on the purples. I would say it looks like a wine purple IRL.
Edited to add: In the picture you can also see the white material at the bottom that is not part of the screen, I would say that is "true white". And the picture also has white pixels on the screen. That's the "dark purple" the review refers to in that case.
I made a palette for colour space conversions for reference: https://imgur.com/a/2vgFsT4