Privacy: what personal data does Apple share with an app developer, when I buy an app?
No personal data is shared with an app developer on app purchase.

The aggregate information available for app units in iTunes Connect App Analytics is:


Purchase date (no more granularity available than cumulative over 24h period)
Device type (e.g. "iPhone" or "iPad")
Platform version (e.g. "iOS 10.3", x.x is the most detail available)
Region (e.g. "Europe" or "Asia Pacific")
Territory (e.g. "United Kingdom")
Source type (e.g. "App Store Search", "App Store Browse")
App referrer (e.g. "Google Chrome", given where a third-party app linked to product page)
Web referrer (e.g. "georgegarside.com")
Campaign (custom string linked to by iTunes product link URL parameter)




When you run the app:


the app can ask you to agree to share your Contacts, which would allow the app to access your ‘me card’ for your name.
the app can ask you to enable Location Services for the app, so the app can obtain your location.


In both of these cases, the app will ask for permission at OS level and you can accept or reject the permission. These permissions are only asked for if the app requests it — it's uncommon to request such information unless the app needs it for your benefit.