I have just discovered this website https://eudat.eu/services/b2find B2FIND is a " discovery service based on metadata steadily harvested from research data collections from EUDAT data centres and other repositories."
They have an API https://eudat.eu/services/userdoc/b2find-usage#Application_Programming_Interface which currently has a Python script (https://github.com/EUDAT-B2FIND/md-ingestion/blob/master/searchB2FIND.py ) but no R interface as far as I know.
It only provides access to metadata about datasets, since the source link of the data can be a link to any repository and therefore it would not be possible to download the data automatically. That said, one of the repos is GBIF http://b2find.eudat.eu/group
Does B2FIND seem to be an interesting resource? I’m not sure yet it’s worth a R package since one could not download the data using it.