I see a lot of people confused how updates get released so I guess I'll get a topic started.
1: There's firstly model differences that get focused on first.
2: There's a difference between "factory unlocked vs "carrier unlocked" and updates are also dependent on those specific differences.
3a: factory ullocked devices get their updates directly from samsung and it's final release is focused on by models.
3:b (Doesn't matter what Carrier service you run on updates go through the factory not carrier on these models)
4a: Carrier locked \ carrier unlocked means you're in the carriers varient, you have a splash screen and Carrier custom rom that displays your carriers logo at boot and maybe modified software that differs from the "factory unlocked models" your updates come from samsung but are dependent on if the carrier approves it and then pushes to your phone via carrier differences.
4b: (Those models are very locked into the carrier regardless if you even have a active carrier and sim in it.)