Switching countries with an Apple Watch

My mum recently bought me an Apple Watch in the US from Verizon because they were running some sort of deal and she knew I’ve wanted one for a while. I live in Australia however and we are unsure if when I go back to Australia if the watch is going to work for me in terms of the cellular option on the watch. According to my mum the guy in the store when she bought the watch said that I would be able to disconnect it from Verizon and connect it to my Australian phone service provider that I have which is Optus. Before I opened the watch I wanted to research and make sure it works and from what most people are saying online it won’t work to connect it to my Australian phone with my Australian phone plan. Can anyone confirm this is true or if they moved from the US to Aus and figured out a way for their watch to work. Thank you!