No such thing, if they are "New". We don't know what happens to the eSIM once they have been activated. AT&T locks the eSIM on the iPad Pro Cellular models so stay tuned.
Note: Apple Watch Series 3 (GPS + Cellular) comes in three regional models – Americas, China, and Europe/Asia Pacific. Unlike iPhone, there isn't a worldwide Apple Watch Series 3 model that supports all cellular bands used globally, so it isn't possible for Apple Watch to roam.
Dave