What are the differences between NetworkBoundResource and RemoteMediator (Paging 3)?
NetworkBoundResource is just a sample helper class wrapping some data backed by both network + db, this has nothing to do with pagination.
RemoteMediator is a Paging3 class which gives you callbacks for when you run out of data to load while paginating using the Paging library. It is typically used to trigger remote loads to fetch additional data for paging in the db + network case.