Hello,
However, to add a new site/service to that list *requires custom Java code* to be written. You'd need to create a new "org.dspace.external.provider.impl.LiveImportDataProvider" class for any new service, similar to the existing LiveImportDataProvider classes all listed in the "external-services.xml" file:
https://github.com/DSpace/DSpace/blob/main/dspace/config/spring/api/external-services.xml
We do not yet have a guide for building your own custom import providers. But, someone familiar with Java coding could look at the existing import provider classes as a guide for how it can be done.
Tim