There is python kasa and a windows app that lets you add devices to your wifi, however i’ve never gotten those to work.
The way i’ve added these devices that need an account is by creating an account and signing into the app. Add the device the normal way, when asked for wifi credentials i entered my IoT credentials. My IoT network does not have internet access.
The device gets added to my wifi but the setup fails, then in HA i then add with IP address.