The point was not about about kamailio modules, but about running a Python script via app_python, which needs to import an external Python library that is not available (upgraded) in Python3 in that distro.
So let's say, only for the sake of example, that I want to use SQLAlchemy in a python script to be run by kamailio via app_python/3, it has to be sure that SQLAlchemy is available for Python3 in that OS version, otherwise I cannot use app_python3.