Have you looked at simply integrating Harmony directly with Hubitat? This would provide you with essentially the same integration between Hubitat/Harmony that exists with ST/Harmony today.
Here is a great post at a method to do exactly that.
Note: This method assumes you have an existing ST/Harmony integration already as you'll need to 'borrow' the keys from it. I'd recommend leaving the integration on ST as removing it would probably break the Hubitat/Harmony integration as well.
I have been using this for a few weeks now, and it works very well for my simple use cases.
