A custom rom has been released of Android Wear 2.0 for the LG G Watch from 2014. That is the first smartwatch with Android Wear that was for sale. The watch does not meet the system requirements and therefore has not received an official update.
According to the developer, to flash the custom rom it is necessary to unlock the bootloader. After that, the new boot.img and system.img can be flashed from fastboot on the watch, whereby a factory reset is not necessary. Then users get Android Wear 2.0 on the G Watch.
The custom rom is a port of the update for the G Watch R, a round watch that LG released a few months after the G Watch. The G Watch R also has a button, something that Android Wear 2.0 assumes. The G Watch does not have a power button that can also serve as a control element.
LG released the G Watch in the summer of 2014 and it was the first watch with Google’s Android Wear operating system. Google released Wear 2.0 last winter as an update for many watches, but many especially older watches do not get the update.
Look back: video review LG G Watch