Most are available "unlocked" now. If not, they can usually be "unlocked" for about $10.
My wife just replaced her S9 due to an exploding battery. The sales people were afraid to touch it, told her it was dangerous and to dump it as fast as she could. It sounded like a lot of baloney, as the battery was expanding slowly so I figure after the exploding versions in the past they modified the batteries to allow them to expand instead.
S9 was starting to refuse some upgrades due to an old O/S version that wouldn't upgrade anymore, anyway. They want their money every few years and will get it from your wallet, one way or another.