I always load WiFi and Bluetooth scanners in my Android gear.
I like to know who and what is talking electronically around me.
Add a MAX30101 to it and you have heart rate and oximeter.
Add 9axis IMU sensor and you can make motion loggers for sports ergonomics research and performance monitoring.
Same thing could be used for movement/music interfacing interpretive dance etc. ie motion input to SonicPI.
Minority report UI.....
To make it a bit thinner use three sections. Zero, IO/Sensors/LCD, battery.
Then it is more a cuff than a watch.
Add more stuff for gauntlet type look, SciFi or SteamPunk?
GPS receiver for mapping, bigger display.
GSM/LTE TX/RX for mobile phone.
LoRa for ??????
Barometric sensor for altitude/variometer = paraglider/hanglider basic flight gear.
All of the above
I'm dancing on Rainbows.
Raspberries are not Apples or Oranges