The (re)pebble probably also falls in this category. It’s a relaunched pebble after Google open sourced the original pebble os it acquired, but then didn’t do anything with. It’s the original pebble founder that is doing this relaunch (you can consider this both good and bad, but I’m sure his intentions are actually good).

It’s of course a commercial product, but at least the software side is open. Battery should last a month (!). Display is always on and readable in daylight.

First of these devices should be about to ship soon, but new orders will take considerably longer.