Buying GPS + Cellular Apple Watch Series 5 in the US - using it in Europe (Switzerland, Swisscom)

If you buy a US GPS + Cellular Apple Watch, is it possible to activate and use in Europe with a supported European carrier? In short, I am hoping to buy the Watch here, explain how to use it to a family member, and have them set up the cell service when they return to Switzerland.

We asked Swisscom what LTE/GSM bands they use, and they overlap with the US model here: https://www.apple.com/watch/cellular/. Apple store employees aren't well equipped to answer this question (some say flat out NO - which I don't believe based on my research). Has anyone bought a recent watch, moved to Europe, and activated it with a European supported carrier? Many thanks!

Note: I understand that some of the US carriers (e.g. AT&T) don't support roaming - that is not the question here. It would be activated with a Swiss-Apple-Watch supported carrier. Thank you in advance

What else am I missing other than (1) checking out if the Swiss carrier is e-sim supported on that list and (2) if that Swiss carrier’s frequency bands are also supported by the US model = which is also true.

Apple Store manager in Miami is adamant without explanation that this wouldn’t work. Anyone have real experiences to share? E.g. moved to Europe with a cellular watch?

Also noticed that as the generations go on (Series 3 to 5) that the band frequency overlap between regions is much greater