Buying Apple Watch 10 GPS in a different Country?
What would happen if I buy apple watch 10 in Taiwan/ Japan and I live in the US?
Apple Watch Series 7, watchOS 10
You would not have a warranty, as they are country specific.
Otherwise the GPS only Apple Watch would work just fine, with the same features/restrictions allowed for the country where you purchased the Apple Watch.
watchOS - Feature Availability - Apple