The correct way should be checking the official documentation for integrating with your target app (Google Pay). In your case you should check how Google recommends to start their activities.
A workaround can be to download the APK (APKMirror) and from the Android Studio select Build \ Analyze APK....
Then you can check all supported deeplinks on the AndroidManifest.xml, but if Google don't want to expose their deep links to other apps then you won't be able to start their app.
Example from v2.106.x:
<activity android:theme="@ref/0x7f1302d1" android:name="com.google.commerce.tapandpay.android.deeplink.DeepLinkActivity" android:exported="true" android:launchMode="2"><intent-filter android:autoVerify="true"><action android:name="android.intent.action.VIEW" /><category android:name="android.intent.category.DEFAULT" /><category android:name="android.intent.category.BROWSABLE" /><data android:scheme="https" android:host="www.android.com" android:path="/payapp" />Important: Even if you have the scheme://host/path you still have to know which query params (if any) they're expecting in order to work. Again, you should honor the official docs.
Hope it helps!
