Okay, I figured it out for Android. It isn't exactly easy (you have to compile with Android Studio and make some tweaks to how that normally works), but it for sure works.
*Export as an Android Studio Project.
*Make sure you have Android Studio installed and running Gradle in the latest version per this Android Developer update.
*Import your project into Android Studio.
*Edit the build.gradle file for your project to insert the code below beneath "dependencies" after marking out the "library modules" section. This is done to prevent errors when compiling your apk since you will now have to use Android Studio to align, sign and compile. Then sync project.
implementation project(':CordovaLib')[/code:2jie87zv]
*Now go to your config.xml file (/res/xml/) and add this line in the appropriate spot to prevent a time-out during emulation for testing. Then sync project. [code:2jie87zv]<preference name="loadUrlTimeoutValue" value="700000" />[/code:2jie87zv]
*Now for the actual app icon- in Android Studio right click the "res" folder in your project (must be in Android view) and go to New --> Image Asset.
*C3 seems to call the app icon "icon" so you'll want to change the image asset name to "icon" and then simply import a 512x512 png file and save it.
To complete the build in Android Studio you'll have to have a keystore and everything, but if you've gotten to this point you probably already know what to do from here. Just make sure to select V1 [b]&[/b] V2 for the Signature Versions to have an aligned and signed apk that is ready for upload.
I've tested the above and it worked perfectly for me (after hours of playing around with things to get to this point since I've always avoided Android Studio). Hopefully it works for some other folks out there.