This is the current bin file that can be uploaded to the Watchy via esptool.
If already using Watchy_GSR, you can use OTA Website and upload the bin to the Watchy from a local file using the Watchy Website at the IP address shown on the Watchy.
If you're not using the Watchy, see the main Watchy_GSR folder for instructions on how to do the upload using the original Watchy face.