Maybe off topic, but 'just in case'.
If you export 'datagridfield' settings from registry and put them in (your profile's) registry.xml: I dont think it works. I needed to put it in setuphandlers. py
plone.api.portal.set_registry_record( 'My.Addon.interfaces.IMySettings.location_names',
[{'location_name': 'Some group', 'something': 'Something'},
{'etc' : 'etc'}, ])
Don't ask me why, but maybe it is this.
Not off topic for me 
- I will make a new thread, going into the consequences of storing DictRow fields in the registry and requiring additional fields that are not visible to the end user (in my case, JWT token and its expiration). This was easy when I had only one connection, but could get interesting now that there are more.
These are the registry values, above we're talking about the registry field creation/definition.