To convert you must download this software ANYTOISO(the given link contains crack)

https://kickass.so/anytoiso-v3-4-2-build-451-incl-crack-tordigger-t6930377.html

Here are the screenshots of the software

I just converted a PS3 pkg file to iso file as you can see

NOTE:

This software can be used to it’s full potential, only when you really needed it