A custom CM14 rom. Working, but not really practical as a watch
Flash with flashtool with Download Only mode over a working firmware.
GAPPS are unstable and make the watch laggy, but you can install them (ARM-Android7.1, https://opengapps.org/)
Pure android, nothing else.
Download: https://drive.google.com/file/d/1eltUpWZ_juBVTAQO2uvFDxUnGeie7OFD/view