I have written a web app using Django. I want to build a device with my raspberry which is always connected to this web app, and shows the result on an e-ink display. I have seen different videos, but I don't understand if this is possible. Can an e-ink display show the gui of raspberry, like a monitor?
Current e-ink displays need several seconds for a screen update. While larger e-ink displays can be selectively updated, several e-ink displays sold for Raspberry Pis can update only the whole display. And this takes around 10 to 15 seconds for some displays, but at least around half a second for some minuscule region.
So, no, you can't use e-ink displays as monitor substitutes (yet). The two main markets for these displays seem to be dedicated ebook readers (read: Amazon Kindle, Rakuten Kobo, ...) and shop price tags. Both trade slow performance for minimal power consumption while the display is static, so we talk about update rates in frames per minute.
Not a GUI, perse; but a pervasive display, yes. Adafruit started distribution of this product late last year; and I have added integration to my project wish list, but I haven't got to doing it yet. Your post reminded me to go over my project build list. However at the moment I'm occupied with 3D Printer Build and other camera projects.