[Q] Serial Number from android armeabi lib

I have an android media box for iptv purpose. The TV app uses a serial number which is also printed onto the device to identify the device. I am trying to understand where this serial number is coming from. I have tried various possible serial numbers but nothing seems to match the serial number it shows in the TV app. I am pretty sure it is reading it from the device itself somehow.

From the code, it seems it is using some native calls to get the serial number. It is using a lib called libPPCoreJni.so which is present under /lib/armeabi in the APK. The native method is called getNativeSN() which I believe is implemented in libPPCoreJni.so.

I have checked the ro.serial number which is empty for the device. I have checked the iSerial file under /sys/class/android_usb/android0/iSerial - it contains the default iSerial which is something like 123456... I am guessing this number is coming from the hardware somehow but can't figure out how.

Does anyone know where else I can check to find where that serial number is coming from and spoof it to test it?

Is the source code for libPPCoreJni.so available somewhere? If so, I could possibly modify that particular method and get it to return a hardcoded serial number, then compile the lib again and replace it in the APK.

Can the .so file be decompiled?

Thanks for your help!