The source code of the ARM64 drivers that we're using can be found here: https://github.com/raspberrypi/windows-drivers
The WoR imager gets the binary packages from: https://github.com/worproject/RPi-Windows-Drivers, where you can also find an updated status of the current hardware support.
UEFI development is done here: https://github.com/pftf
There is also a Discord server for discussions: https://discordapp.com/invite/fqRhc8y
The easiest way of contributing to the WoR tool is by adding/updating translations. The repository can be found here: https://github.com/worproject/WoR-Translations
We also have a bug tracker page where you can report issues or suggest features: https://www.worproject.ml/bugtracker