E-ink displays are expensive. Not those abandoned e-price tags though! I got 5 of them for less than $1 each. They are made by Blozi which no longer exists. Their loss is my gain. I'll see what I can do with them.

I found that there is a a project that already has a firmware and Android app to update the content. The firmware is based on the TI official examples. 

CC2640 is a MCU with abundant resources and example so it should be not very hard to get started. 

The only thing is that it requires JTAG to re-program the chip. I don't have one and it can be very expensive.

Fortunately I found the blackmagic project for ESP32 and I bought a few ESP32 dev boards for future projects and they have been used yet. So I guess this will be my first ESP32 project.

If everything goes well, I will be able to use ESP32 to flash the CC2540 MCU. Then the next step is to have a firmware that run the BLE stack and takes commands from a Bluetooth broadcaster, i.e. my raspberry pi 4 running HomeAssistant. Eventually I will have theses previous price tags around my home display various interesting status or images.