The App Inventor 2 source file is the aia file. The aia file is a form of *.zip file. You can unzip the file and inspect the youngandroidproject.
Using a copy of your AI2 aia file:
Change the suffix from aia to zip. For example, MyApp.aia ..change it to MyApp.zip.
Now, unzip MyApp.zip . Look at the resulting folders. Did you find what you need?
Regards,
Steve