ugi
I didn't write it up anywhere, I might at some point, but free time/willpower I have to spend on it is minimal. Although I have an itch to make a v2 with a combo of rp2350 and nrf52840
If you're interested here is the devkit I was using it's this: https://www.waveshare.com/esp32-c6-touch-amoled-2.06.htm
Apart from some unfortunate GPIO pin selection they made, and a bit of bugs and missing features in esp rust hal, it wasn't that bad to work with.
But in the end, what I'm using it for is notifications, time, timer or stopwatch, and glanceable weather forecast. (And I don't like the weather forecast on android/google wear)
Everything else, like sleep tracking, exercise, heart rate tracking, is a nice to have that I would look at from time to time and then do nothing with that information.
Anyways, a month or so ago I bought an amoled esp32c6 watch devkit for ~30 EUR, wrote firmware in rust, wrote a small android app to sync notifications, time and weather forecast, and I'm good. It's buggy and I need to polish it up, but it's exactly what I need. And if I ever need something else, I can just add it. Of course this is an extreme approach. It would be much easier to buy a cheap fitness tracker that does all this and has much longer battery life. I just like to be able to tinker with things.