For quite some time, Nokia 6 has been available in the United States, mainly as an Amazon exclusive. Amazon offered the device for just $229 (€195), but there was an option to pay $50 less for the device by choosing the “Amazon Prime” edition, that displays ads on the lockscreen. Now, Prime members can get the 6 for just $149 (€126), but with the downside of ads appearing on your lockscreen. The regular Nokia 6 (without Amazon ads) still costs $229 and there is an option if you buy an “Amazon Prime” edition with ads and don’t like the ads, to pay the difference so the ads disappear.
You can check the offer here. The device is GSM, meaning it works on GSM networks from AT&T, T-Mobile and others.