Why is there no German GP even though there is a German F1 driver, but two Italian GPs even though there is no Italian driver (F1)?

This depends on the entrance fees that Formula 1 requires that they carry out a Grand Prix on a track. The costs have, of course, increased further in recent years. The route operators in Italy seem to be able to stop them while they are more likely to be a loss business for Nürburgring or Hockenheimring. Or the tickets would have to be so expensive that hardly anyone would watch. The massive increase in prices is also due to new routes such as Qatar or Saudi Arabia, the much higher numbers of entry fees, which is why conventional race tracks are under pressure. The development is not so new.