To connect your LG G Watch R with your PC:

be sure you have the latest SDK (ADB & Fastboot) installed

on your Watch enable Developer Options

"OK Google" -> Settings - about Device

Tab Build Number 7 times

go back to main Settings

enter Developer Options

enable ADB Debugging

Connect your watch with the Charging Dock to your PC

In Shell/Terminal/cmd

Quote: adb devices

Now you can use ADB and Fastboot:

Quote: adb reboot bootloader

Quote: adb reboot recovery

ATTENTION:

Quote: fastboot oem unlock -> opens the info to unlock your Bootloader Unlock will VOID your Warranty

Quote: fastboot oem lock -> will lock the bootloader agian confirmed by @dclaw_fantum

Quote: I have tested this: It does lock the bootloader back to locked status. The little lock icon on the LG logo also goes away when the command is executed successfully.

Disclaimer

typeto check if your Device is there-> will bring you easy in Fastboot mode-> reboots the watch into Recovery ModeYour warranty is now void as soon the Bootloader is unlocked.I am not responsible for bricked devices, dead SD cards,thermonuclear war, or you getting fired because the alarm app failed. Pleasedo some research if you have any concerns about features included in this ROMbefore flashing it! YOU are choosing to make these modifications, and ifyou point the finger at me for messing up your device, I will laugh at you. Hard. A lot.Thanks @ eSportler for the tip