Source Wireframe Kit - Library of 537 blocks for desktop and mobile prototyping
Wear Gesture Launcher - Wear Gesture Launcher – Wear OS – Wear Launcher that lets you forget about swiping that long of small icons, just tap, draw, and do.
Platforma - Wireframe library of layouts and UI elements
Wear OS by Google Smartwatch - Wear OS by Google Smartwatch (was Android Wear) is a powerful app that syncs your smartwatch and phone so you can get more 0ut of your watch.
Form Wireframe Kit by InVision - A free wireframe kit from InVision
wasp-os - Firmware for smart watches based on the nRF52 family of microcontrollers (including Pine64 PineTime)