Garmin already markets a watch with more than is really needed. The tactix 7 Pro Ballistic Edition weighs only 89g. Beyond the ‘normal’ smart watch features, it supports solar charging, GPS, GLONASS and Galileo.
Too many other features to list but take a look at
https://www.garmin.com/en-US/p/802901#overview, if you’re interested. Of course, a ton of the features will likely be non-functional at wake up.
For MP, I’d probably want to add a dosimeter.