Wish is similar to Aliexpress in that it is just a marketplace over which various merchants sell merchandise.
Many merchants operate from China or other Asian countries. Like Aliexpress, Wish is driven by low prices.
The mobile-first strategy means that the app is the key element of the service.
The app is becoming more popular in Switzerland, but that likely doesn't have much to do with the quality of the products offered. The retail service has not scored outstandingly in terms of quality or reliability in independent tests.