I am currently working on reverse engineering a few off the shelf eink shelf labels to be hacker-friendly and open. Watch for it on my usual project site in a week or two. (link in profile)
Why don’t you statically allocate local IPs for each esp32 you have and have each one of them run their own simple web server. Then just print out a qr code that points your phone to the IP address of that device and have the device serve up information on your phone rather than an eink display. That way there is no need for the qr code to change and therefore no need for an eink display.
I have a ttgo t5: http://www.lilygo.cn/prod_view.aspx?TypeId=50031&Id=1149&FId...
Seems to match what you are looking for, with an esp32, an e-ink display and a battery connection. It is also quite cheap. I use mine as a weather station.
Didn't see how to buy them but this might point you in the right direction if you haven't seen it. https://hackaday.com/2019/02/25/e-ink-price-tags-fall-off-st...
https://www.eink.com/electronic-shelf-label.html?type=applic...
Often programmed with overhead infrared emitters.
Sadly out of stock: https://www.adafruit.com/product/4800
Been scouting for eink labels and these I found in the wild. No clue if this is what you're looking for but it's as far as I'm able to help.
Best* Buy - Pricer
Lowes - Chroma 74
> Recently one of my friend purchase this ...
https://www.amazon.com/DYMO-LabelWriter-Super-Bundle-Multi-P...
>long battery life - wifi networking to update display OTA
Wifi is massive overkill for this kind of application and will be very difficult to make work for the power profile you want. Check out an alternative 2.4ghz protocol like zigbee, aka: https://hackaday.io/project/165467-papyr-nrf52840-epaper-dis....
You can buy a zigbee router for less than 5 bucks, plug it into a pi zero and you have a zigbee > wifi bridge for less than 10 bucks.