Yes, you can use your Hamony Hub with Hubitat using the integration that I wrote a while back. It will create a child 'switch' device for all of your Activities, including one called "PowerOff". There is always one, and only one of these Activity switches in the 'On' state. If none of your actual Activites are 'on', the "PowerOff" one will be 'on'.
The one thing people miss is the fact that there is no way to associate Hubitat devices to the Harmony remote control's 'smart device' buttons. This is due to the fact that the integration is a direct connection to the Harmony Hub over the LAN, and there is no way to make that association that I have found. If you have Phlips Hue or Lutron, you can directly associate those devices with those remote control buttons using their Logitech integrations. Unfortunately, Logitech is not accepting any more integrations, otherwise Hubitat would have done so already.
