Basically, there are 3 described areas in the bathroom: 0, 1 and 2.
In area 1, at least a protection class of IPx4 is required. The permitted equipment in this area is limited to towel radiators, exhaust fans, shower or whirlpool pumps. Generally, the use of SELV or PELV loads is also permitted, up to a nominal voltage of 25VAC.
The manufacturer should explicitly state that the installation of his product is permitted in area 1. In case of doubt, an electrician must always be consulted.
In area 2, only devices with at least IP protection X4 (splash water protection on all sides) may be installed.
Sockets may not be located in either area 1 or 2. The entire installation in the bathroom must be protected by a residual current device.
This information is without guarantee. The current Swiss NIN applies. In case of doubt, please consult a trained specialist.