US zwave frequency ( technically North American zwave frequency), same as US voltage, but the grounding is sometimes different so not all mains powered electrical devices from the US will work in all areas in Mexico. But most will work. See the following:
Zwave Devices are very popular in Mexico, I don’t see any reason not to use them with the US model of the SmartThings hub except for the grounding issue that I mentioned, and that only affects some individual devices. All the battery powered Z wave devices, for example, should be fine as long as they’re on the North American frequency.