(www.androidauthority.com)
If there are only four words per line, you can slide your eyes down the middle and take in all the words in a chunk like you would for normal speed-reading.
I have an xteink X4 and X3 and I swear I can read for much longer without strain. You can also just crank your margins way up on most other e-readers.
A recent article on HN convinced me to try the M5Stack Paper S3. Much nicer screen with 16-level grayscale touchscreen, microSD slot, ESP32-S3 with WiFi and Bluetooth, supports the Crosspoint Reader software. It's got a magnetic back but won't fit on the back of a Magsafe phone like the Xteink4 can. It's double the price, but well worth it.