The news makes the rounds. Regarding to ppi densitiy:
"FYI: The reason this device has a screen resolution of 150ppi has to do with how it gets its color. This is actually a 300 ppi grayscale Carta E-ink screen with an RGBC filter applied on top. The filter adds red, green, or blue on top of a pixel on the E-ink screen (the C is for "clear"). The filter requires 4 pixels on the grayscale screen underneath to give you a single pixel on top This reduces the resolution to 150 ppi."
source:
https://the-digital-reader.com/2018/...-e-ink-screen/