The GPS only Apple Watch (or a cellular that has not been activated, or a cellular that is traveling out of country) can do Everything the activated Cellular model can do AS LONG AS your iPhone is nearby, where nearby is generally somewhere in the same moderately sized home. The Cellular model allows you to leave your iPhone at home while you go for a walk, run, bike ride.
The Cellular + GPS Apple Watch shares the iPhone's phone number, and the carriers that support the Apple Watch charge a monthly fee. In the U.S. the fee is $10 per month. Here is a list of carriers that support the Apple Watch:
https://www.apple.com/watch/cellular
NOTE: It is not whether the cellular carrier offers eSIM support, it is whether the cellular provider actually supports the Apple Watch sharing your iPhone phone number.