I want to know mobile network operator from unity apk file
unity might be too sandboxed on an android phone for this, but you can do this kind of data hunt with c# and xamarin, which is a very powerful mobile device toolkit and it might provide some hints for you
You can create an aar file that uses Android Telephony Manager
Telephony Manager will have most of the sim card info you will need
As per Android Docs:
Provides access to information about the telephony services on the device. Applications can use the methods in this class to determine telephony services and states, as well as to access some types of subscriber information. Applications can also register a listener to receive notification of telephony state changes.