I'm working on redesigning my  Watch app and was frustrated that there isn't a segmented control available for watchOS, so I did a little exploration imagining how a control could work on a tiny screen.

Still not sure if it is a good idea, but think this approach certainly has enough promise to continue exploration.

After sleeping on it I think I'm going to shelf the vertical segmented control for now. It just doesn't work on a 40mm, it would take up over half the screen at appropriate touch target sizes. Instead I'm going with horizontal segments with icons. With the "explanation label" as a subtitle for the relevant settings section to make it clear what the choice does.
@_Davidsmith looks great!