According to my informations, VoLTE and Wireless Calling is supported, if your provider offers it as well. For further information contact your service provider directly.

The device can only be used with European SIM cards.

Yes, of course. Simply buy a prepaid card from a telephone company (Swisscom, etc.).

Non.

256GB laut Herstellerseite: https://www.samsung.com/de/support/mobile-devices/welche-speicherkarte-passt-in-mein-galaxy-smartphone-tablet/

Hello Samsung Galaxy phones only allow European sim cards, if you have one then yes. https://www.golem.de/news/samsung-galaxy-smartphones-gestatten-nur-europaeische-sim-karten-1309-101816.html

The plug is two-pole and fits into sockets in both Germany and Switzerland

Yes, that is unfortunately correct.

Dual-SIM Dual-Standby

There are several ways to copy the contacts. Instructions can be found on Google - simply enter "copy contacts from iPhone to Android" as a search term.

The box of the device says "Europe Sim Only". Unfortunately, this is not stated anywhere else at Digitec. So it probably won't work. I only noticed this when I received the device, but since I don't use it myself, it doesn't bother me.

Unknown. At most, the person who had the phone before can tell you. As good as new is simply the optical condition. In most cases, however, it is a mobile phone that someone did not like and returned. Then it is as good as new.

if it is on stock (as this one is), it usually takes them one day to deliver the product. You can either pick it up at a shop or choose home delivery.

Digitec only ships products to Switzerland and Liechtenstein. They do not ship to any other countries.