Be advised that the connection between Home Assistant and Hubitat is local whereas the official one for SmartThings (SmartThings integration) is not and works via SmartThing’s cloud API.
There is a way to establish a local SmartThings connection but it is a custom solution called SmartThings MQTT Bridge.
There is no official Hubitat integration but there is a custom solution that uses Hubitat’s Maker API (i.e. local connection).