From a Yanko Design online review:
Designed to universally retrofit onto most curtain rods, the SwitchBot comes with two hooks that hold it in place and a wheel that moves the bot left or right. Place the SwitchBot between the first and second loops of your curtain or blind, and the bot can now, on command, run up and down the curtain rod, maneuvering your curtains open or closed. SwitchBot runs on an app, but even supports voice commands via your phone or smart speaker, effectively allowing you to have your own “Let there be light” moment by commanding the curtains to open at will. IFTTT and shortcuts support even lets you sync SwitchBot with your alarm, or with the time of the day, thanks to the bot’s in-built light sensor.