The global administrator request in this case is called consent(https://docs.microsoft.com/en-us/azure/active-directory/manage-apps/configure-admin-consent-workflow), ( https://docs.microsoft.com/en-us/azure/active-directory/manage-apps/configure-admin-consent-workflow ) this provides permission to use the app that allows NWC to connect with SharePoint and not the permissions used by the connection to perform the operation.
The connection uses the permission of the user who created that connection and they will not have any access they did not have in SharePoint. So in your case you would need to have 2 connections with the required access level(https://help.nintex.com/en-US/nwc/Content/Designer/Connectors/SharePointOnlineConnector.htm). ( https://help.nintex.com/en-US/nwc/Content/Designer/Connectors/SharePointOnlineConnector.htm ) These could be created by the end user using their permissions or potentially using service accounts if you would prefer.
I would also recommend restricting access to use the connection in workflows to stop unauthorised users using that connection(https://help.nintex.com/en-US/nwc/Content/Dashboard/Connections.htm). ( https://help.nintex.com/en-US/nwc/Content/Dashboard/Connections.htm )
Please let us know if you have any further questions,
Cheers,
Leigh
Thanks for your comments. Its quite helpful. My humble opinion is: When we try to create the connection for the first time - It should let users know that there will be a one time Azure Global Admin Consent required and following users wouldn't need to get this consent.
Thanks,
Santhosh