Where does libc.so come from on android app?

The callstack from firebase crashlytics contains a lot of unsymbolized functions from android native library ( libc.so, libui.so, libbinder.so .... )
I'm tring to know what is the function.
But i don't know how to get debug symbols of the shared libraries.
I even don't know where shared libraries come from.
Is it contained in apk file or Is it loaded from what user device has?