Dataflow vs Dataset refresh

>So I assume the dataflow is much like a data storage component on its own that manages the updating from the data source, wherever that may be

That's correct, technically PBI's Dataflow uses Azure Data Lake Gen2 for storage.

One use case I plan to use this dual refresh structure for, is to handle sources (e.g. static files) that don't need to be refreshed in Dataflows where they'll be imported but not under scheduled refresh. I've found PBI's scheduled refreshes to fail easily, so cutting down the service's scheduled refreshes to sources that actually need to be refreshed should lower incidents (e.g. web API timeouts, credential issues etc.).