So, in recent OLAC presentation I talked about enabling Omeka or Drupal via recipes for OAI harvesting. Here is some links to internet chatter on these issues.
Koha
enable Items in KOHA OAI Harvesting
https://koha-community.org/manual/18.05/en/html/webservices.html
wordpress
Day 13: Harvest data with OAI-PMH
WordPress and Drupal
eHive
Catmandu
https://librecatproject.wordpress.com/tutorial/
Omeka
https://omeka.org/classic/docs/Plugins/OaiPmhRepository/