Have you shared this on /r/HomeAutomation and /r/HomeAssistant?

Much less technical crowd in general than HN, but framing old tablets (as informational displays of 'smart home' state etc.) is quite popular, and I think your project is much more suited to it: much lower-power (such a device is only useful if always-on really), and much less distracting (e-paper not glaring bright colourful iPad or whatever).

Looks great, I'd definitely be interested at $59 (in £) if it's sufficiently/easily enough hackable!