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Battery/Chargeable e-ink displays integration
(feddit.uk)
Home Assistant is open source home automation that puts local control and privacy first. Powered by a worldwide community of tinkerers and DIY enthusiasts. Perfect to run on a Raspberry Pi or a local server. Available for free at home-assistant.io
Check out these maybe:
https://dmitry.gr/?r=05.Projects&proj=29.%20eInk%20Price%20Tags
http://furrtek.free.fr/index.php?a=esl
There's more but I'd have to search for it, it's a good starting point though.