LilyGo T5[0] has some different (smaller) sizes that seem quite good and cheap. They even have an option for battery and touch capabilities. And if eInk isn't required, they have some weirder types of devices with screens for tinkerers, like glasses and watches. Not Linux but ESP32, but I think in that form factor and performance it's preferable. Haven't tried them myself though, but they seem quite popular, my cursor has been hovering over the buy buttons for months. They usually don't come with case but there's a ton of 3d printable options and also some ready ones on Aliexpress.
It would be powered by USB C, have a small Linux system installed, and some easy way to display stuff on the screen. In a nice case.