Switzerland is a nation-state on Earth's European continent. People or things originating from Switzerland are Swiss.
In 2357, Liam de Gaillimhe promised to meet Daniel Radke at Wieholme Ski Lodge in Switzerland. De Gaillimhe never showed up. (Star Trek: The Cantabrian Expeditions: "White Flag")
Captain Rafe Mahler was born and raised in Switerland. (Star Trek: The Prospect Chronicles, Star Trek: Shabonee)