Not many travelers here list state Schleswig-Holstein in their itineraries.
Maybe this picture series from an online presentation of an illustrated book will improve the demand:
https://www.n-tv.de/mediathek/bilderserien/panorama/So-schoen-ist-Schleswig-Holstein-id30695396.html
I can deeply recommend it from living in this state for some years; my parents lived close to Fehmarn island in their retirement years.
Of course I am not commercially involved in any way.
Enjoy.