It’s best to always use the hue bridge. See the FAQ (this is a clickable link)
And if you are using the hue bridge, assuming you can get an account set up, you should at least be able to use the free IFTTT service for some Hue integration.
I don’t think you’ll be able to get the harmony to work directly for the same reason you can’t get the hue bridge to work: you are region locked as long as your location is in New Zealand. But again, you can use IFTTT for some integration:
But if all you want are zigbee devices, have you considered using the echo plus or echo show (second generation) as a home hub instead? Uses the same home automation profile for zigbee that smartthings does, and they are adding more features all the time.