This content was released on Jan 19 2021. The official support period is 6-months from this date.
On watchOS, you can either tap to interact with SwiftUI sliders, or use the Digital Crown. Bulb Buddy uses a slider for hue, saturation, and brightness.
This is a companion discussion topic for the original entry at https://www.kodeco.com/20088887-smart-lighting-with-homekit-in-watchos/lessons/4