Xamarin.Android Exported activity without intent filter accessible to other apps

Goal

Confirm whether a Xamarin.Android activity declared with [Activity(Exported = true)] and no intent filter remains accessible to any installed app after manifest merger on Android 12 (API 31) or higher.

Constraint

Android 12 requires an explicit android:exported declaration for components with intent filters, and library manifest merger can override the source attribute. Xamarin is out of support, so newer platform security requirements may not appear in older templates. It is also unclear whether Xamarin.Forms Shell or Xamarin.Essentials file and web features implicitly mark components as exported across versions.

Questions

• Does Exported = true without an intent filter make the activity startable by other apps after manifest merger?
• Does Xamarin.Forms Shell or Xamarin.Essentials implicitly set android:exported on any component?
• Which effective android:exported value governs when the attribute and merged manifest disagree?