I am going to visit the USA for a few days. I am planning to buy an iPhone X during my trip. During the buying process on the Apple Store, I am asked to select a carrier between AT&T, T-Mobile, Sprint and Verzion. Is this important to activate the iPhone? I dot not have any sim from the USA and I am not planning to have one for using the iPhone X over there.

Edit:

I think it´s not possible to buy it without having a current carrier in the USA. I selected one carrier and it's asking me to put my number and a pin to be able to buy it. I tried to chat with them and ask but chat does not work outside the USA. Can someone ask them please?