AsteroidOS is a free and open-source smartwatch platform based on OpenEmbedded, libhybris and Qt5.
You can fully build a flashable image from source with the following commands, but be careful it will take several hours:
. ./prepare-build.sh <your machine id, e.g., dory>
bitbake asteroid-image
For more information report to the documentation.
Stay tuned about the project on Matrix and Twitter.
Report any problem on the project's issues tracker.