There is a way to add some metadata to AndroidManifest.xml for an app, a service or an activity (https://stackoverflow.com/a/38699357/1263771):
<application android:icon="@drawable/icon" android:label="@string/app_name">
<meta-data android:name="my_test_metagadata" android:value="testValue" />
......
</application>
How to get that metadata from the installed app by the adb command?