Question about Apple iPhone 12 Pro

The CH providers use the following 5G bands:

Swisscom:
N1 - 2100 MHz - 5g wide
N78 - 3500MHz 5G+

Sunrise:
N28 - 700 MHz
N78 - 3500 MHz
N80 - 1800 MHz -> planned

Salt:
N75 - 700 MHz -> planned
N78- 3500 MHz -> planned


Swisscom says the band N1 5G wide and the band N78 5G+. Both bands are supported at Swisscom.
Salt has not yet switched on its 5G or only at 1 or 2 test locations. Sunrise has also planned band N80.

So you will be able to use all currently active bands.