The Logitech Harmony App on your mobile phone has no Hubitat integration options that I am aware of. My Logitech Harmony Hub driver simply requires one to manually add a virtual device in Hubitat, and assign the IP Address of the Harmony Hub to the user preference settings and click save. It then connects directly to the Harmony Hub via webSockets and will automatically create a child device for each Harmony Activity. The Harmony App on the phone is not used for this integration.
That's some good feedback. Glad to hear it's working fine for your setup.