I’ve had both T-Mobile and Sprint versions, both have been used and activated with T-Mobile and Verizon SIM’s. If you pay in full at the Apple store, they all come unlocked, just make sure you purchase as “device only” and don’t request activation.
Thanks, I know the "from apple paid off in full or iUp (my own iphone X as well as my last iphone 7+ is using t-Mobile via iUp, both are unlock) that comes unlock" but I got my GF a second one via T-Mobile to take advantage of the $300 trade-in so it will be via a 24 months payment plan. I just didn't know they won't unlock it in that situation. Anyone has any luck to get unlock when the device is still in payments?