The color screen of e-readers is too dark for me and substantially lacks contrast. It’s very noticable. The layer for pen recognition already makes the screen darker, but the color display is adding a lot more to the darkness and lack of contrast. I would only go with an e-reader with black/white screen and even without pen recognition.
Furthermore, e-readers are much more fragile than mobile phones. The design of their screen leads to a high probability of getting broken which is a common thing, search “ereader screen broken” online. My Boox e-reader fell 50 centimeters and the screen was broken, which renders the whole devide unresponsive.
The pen recognition is not as precise as on tablets. You can draw with it, but it’s a bit annoying and not for detailed work.
So my suggestion is to go with a device that costs less than 200 USD and do anything else than reading on a phone or tablet.