I have some relevant experience. I built this a few years ago:

https://imgur.com/a/diy-automatic-e-ink-newspaper-using-rust...

After careful optimization, the v1 got about 6 months out of a 1100 mAh battery. Later improvements and bumping to a 3300 mAh battery got me to 14 months, before my kid yanked it off the wall, total'd the panel and I rebuilt it. The test continues.

That said--op isn't wrong. If power usage is the metric you optimize for, there's much better BOM than an esp32.