Same here… I’d be really interested too. With a tablet you pretty much have to keep it plugged in all the time. A battery life of several months would be a dream…
Indeed Trmnl is very prominent in the Home Assistant (HA) world, but it’s expensive. On the other hand there are very cheap e-ink displays on Aliexpress that can be assembled with an ESP32 and a small 3D-printed case and that is really economical and inexpensive.
I’m going to dig in that direction and take inspiration from these videos for the DIY: