Few months ago, I got a Weloop Tommy smart-watch from work. I played with it a little bit, but quickly put it aside, until someone recently reminded me about this open source firmware called OSSW (the corresponding Hackaday.io project page can be found here). I thought it would be a great sandbox to start playing with the watch, but building the FW was only possible using Keil and Windows...
For this reason, I set up a fork on my Github account that has been adapted to build on Linux (or Cygwin) using GCC. It can be found here.