Displaying Apple Health graphs on an e-ink display

I’ve had this idea for some time to use a low power device to show Apple Health metrics on an e-ink display. There have been several project examples like this one but most use an expensive e-ink display of > $200 USD. But before trying to prematurely optimize, let me go nail down my exact requirements

Querying health data

How do I query my personal health data from Apple Health? I need regular updates so manually exporting and parsing is probably a deal breaker. Based on searching, it appears that Apple doesn’t allow querying the data via a REST API directly. So it has to be from an app running on the phone/watch which has to be explicitly given permission to access health data.

Withings API (MVP)

But I’m using some other apps on my phone like Withings which has access to a subset of the Health data. If Withings allows me to query via web, then it’s probably a workaround I could use - basically query Apple Health data via Withings’ REST API. Based on this video Explore and Visualize data with the Withings API | Youtube what I’m thinking about is possible with the following steps:

Create a whitings app (WithingsTalker) using the developer dashboard
Request premising to grant health data read access to the app. Approve request by signing in using personal credentials.
Start saving the data (localhost initially)

Given that Withings developer dashboard allows setting ‘localhost’ as one of the approved URLs for an app to pull data, I can just start with running a local server on a raspberry pi to request this data as ‘localhost’

So this will cost $0.

Now, assuming I have the structured data to display, it needs to be pushed to the E-Ink Display.

Connecting E-Ink display with the server

Hardwire (MVP)

The easiest way to prototype would be to connect the E-Ink display directly to the raspberry PI running WithingsTalker. If it’s hard wired anyways then both data and power aren’t a problem.

ESP-32

The E-Ink display could also be driven by a low power ESP-32 board with a wifi module. In that case, it could be made completely mobile but will need its own power source. I can check options for batteries and see if that’s something

Purchase E-Ink display

One thing that I made pretty clear that I didn’t want it to be one of the expensive displays available in the market. I’d only buy one of the larger ones if I can get a used one in decent condition.

Waveshare: > $60

Looking at reddit for reviews and prices, many are pointing towards Waveshare. Example: 5.65″ - 13.3″ - e-Paper - Displays but I didn’t expect them to the this expensive. The medium sized are over >60. Waveshare is selling an entire color 7.3in Photo frame for $86: 7.3inch ACeP 7-Color E-Paper with Solid Wood Photo Frame| PhotoPainter