Sprint has multiple colors of the 512GB iPhone XS for $599 (New). This can be used with their $35 kickstarter unlimited plan. Needs to be on Sprint for 50 days before they will unlock and you can goto another network if desired. I ordered 2 in-store and they waived the activation fee as I am coming over from AT+T. Planning to try Sprint and if I don't like going back to AT+T on a BYOD plan after 50 days.
As I understand it, 50 days is just random.
There is a formal "understanding" agreed to by major mobile operators in the USA that handsets can be unlocked after one year if considered paid and acct. in good standing.