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!
Hadn't heard of Homey.app that that's for, but yes I guess what I'm suggesting is that Paperd.ink could be a good 'that, but for people that DIY with HomeAssistant/OpenHAB/whatever'.
Using a Kobo eReader on the other hand is a great purpose for when you’re not using it. Now when I leave for holiday I just take it from the wall :)