Hi , App Clip is great for user to scan NFC Tags . But I found that , when user first scan the NFC Tags with associated URL in it , the app clip receive the userActivity is empty. not only for NFC Tags , also appear on QR Code.
Another things, when you scan the NFC Tags with URL in it , which associated the app. The App Clip card appear. but cannot receive any ndefMessagePayload in userActivity (only for NFC Tags).
Before App Clip appear, in iOS 13 & iOS 12. when you scan the NFC Tags with URL in it , which associated the app. you can receive ndefMessagePayload in userActivity.