I don't think I agree with your assessment of this for the following reasons:

1. Nothing here is being tracked "across other companies apps and websites", unless there's something here that shows Apple is cross-pollinating their data internally (which is possible but I don't see any evidence for here).

2. I disagree that this includes "App Store" app. The description given when you click the "About Analytics & Privacy" link explicitly states what the differentiation is and, to me, that does not include the App Store app.