RSS 1.0 is XML / RDF based, so you would need to create an XML Schema document that matches the spec of the feed you want to consume. Once you have that, you can create an Import Mapping that uses the XML Schema. This can be used to create the entities you need for your Data Grid.

To import the data, create a microflow that has a Call REST Service action, and apply your Import Mapping to the Response. You should then be able to pass this into a Data Grid.

Hope this helps.