KeyFrameAnimations and SwiftUI charts

I watched both sessions. At the end of the keyframe animations session, the presenter at 16:42 shows the KeyFrameTimeline and its API.

// Keyframes
let myKeyframes = KeyframeTimeline(initialValue: CGPoint.zero) {
    KeyframeTrack(\.x) {...}
    KeyframeTrack(\.y) {...}
}
// Duration in seconds
let duration: TimeInterval = myKeyframes.duration
// Value for time
let value = myKeyframes.value (time: 1.2)

Then he says that he used this to draw the charts seen earlier in the WWDC sessions.

I thought that he used the instance of a KeyFrameTimeline directly in Chart() to make a graph of the variables and values over time. If trying to to it I get the error message that KeyFrameTimeline needs to conform to Random Access Collection.

So maybe I am missing something? I am curious to see how that would work! And how to make a graph for each KeyframeTrack inside my KeyframeTimeline