How to extend
The Pacemaker Import Community functionality by design works standalone.
It is possible to use the Magento directory
<magento-install-dir>/app/code/ to extend
the Pacemaker Import Community functionality without deploying it as a Composer library.
When do I need to override/extend a existing Pacemaker default class?
If additional attributes have to get added to a non-EAV entity
If the import is to continue when a website referenced in the import CSV file is not available in the Magento instance
If a minimal Magento module must get created
In any project that uses the Pacemaker module, it is called