Add custom information into application descriptor?

you can also add metadata to the SWF file itself

see: Adding metadata to SWF files​

and then at loading times you can read the loaderInfo.bytes to parse and get back that data

and/or you can use a custom metadata in AS3
eg.

[mystuff(name="foobar", desc="something")]
public class Whatever {}

then in compiler options use keep-as3-metadata=mystuff

then in AS3 use describeType to get the values etc.

see Using Custom Metadata Tags

for android add a custom meta to xml manifest file.

<meta-data android:name="send_launch_scheme" android:value="xdev" />

then read that value from metada property of ApplicationInfo

private String readMetaScheme(){
        String send_launch_scheme = null;
        try {
            ApplicationInfo ai = getPackageManager().getApplicationInfo(getPackageName(), PackageManager.GET_META_DATA);
            Bundle bundle = ai.metaData;
            send_launch_scheme = bundle.getString("send_launch_scheme");
        } catch (NameNotFoundException e) {
            Log.e(TAG, "Failed to load meta-data, NameNotFound: " + e.getMessage());
        } catch (NullPointerException e) {
            Log.e(TAG, "Failed to load meta-data, NullPointer: " + e.getMessage());         
        }
        return send_launch_scheme;
    }

It depends on your platform, but you could try putting it in the description field?  I'm not sure that the description field is used at all on Android or iOS, but I haven't checked the bundle to see if the field has also been stripped.  It also won't help you on other platforms.

Loving your ANE's by the way.