It’s the same as any Android 10 device.
So easy to find on xda etc…
However, I think the bootloader unlock is disabled on the recent firmware.
But you can read up about it and check.
The reason why we don’t discuss this very often is the fact that root on Android 10 system as root is pretty useless and not worth the effort.
Any changes you make will upset the system verity and end up with a bootloop message “system has been tampered with”.
This can only be fixed if you flash the firmware again.
About the D09_2021.05.21.7z(old beta version) - it is no longer available or supported (even if you have managed to download it) and yes it has problems which is why it was discontinued weeks ago.
There is a new beta being tested privately and when it is ready it will be published.
FAW International Firmware Beta Testing Project - is Back! - Announcements - Full Android Watch
FAW firmware is stock firmware that is built from the same stock source by us, in partnership with the Chinese owners. The solutions providers.
They asked us to make it.
It is called the International version because it is specifically built for users that can make full use of Google apps - because in China they can’t.
So it is built using the intended Android structure without customised apps which cause battery drain and security issues.
It is not possible to root it - intentionally.
For the same reasons mentioned above.