If you're looking for an alternative to all of this, the BangleJS v2 is both cheaper and more hackable than the Pebble watches. It doesn't tick all of the same boxes, but it's performed well for me over the last 6 months.

Here's what it offers:

* Screen is fully visible under direct sunlight

* With the screen always on the battery lasts me well over a week

* Heart rate monitor

* EXTREMELY hackable, everything can be hacked on with JS, even the launcher you're using for apps

* 108 Euros shipped to the US

* Fully supported by GadgetBridge (open source mobile app)

https://www.espruino.com/Bangle.js2

Don't remove that little tape that prevents the watch from shocking you with 3 continuous volts of electricity!

Thanks for posting, I love getting gadgets with niche displays, a 3 bit color sun readable display, how peculiar!