It's in the wearable's Settings menu, in the Developers Options section. I couldn't find any information about it, nothing in the documentation either.
What are the potential use case scenarios of this feature?

Note: to unlock the Developers Options section, tap 7 times on the About item.
It creates a log file of all the Bluetooth traffic to and from your device, for analysis purposes.
Edit: Adding @BrentM's comment:
The log file is saved to /sdcard/btsnoop_hci.log. Take a look at this question, it is not specifically for wear, but wear should follow the same work flow: Sniffing/logging your own Android Bluetooth traffic
If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
Donate Us With