Angel Watch™ is fully unlocked and will work on just about all global networks (4G/GSM/LTE).
Wherever you are, you can select any plan that has voice and data, around 1000 minutes (~17hrs) and 1GB. This is usually plenty.
You will also just have to make sure to update your watch's APN setting to the Android setting of your network provider. You can search online for: "what are (your provider) android APN settings" and you'll be able to select the correct APN setting on the watch and connect to the 4G data you'll need.
You'll need to check your network's APN settings for 4G Android devices and make sure this is selected/entered into the watch's APN settings (Settings-Mobile Networks-APN).
If your question is What networks are compatible in the USA? please go here.