Isn't there a way to allow the devices to be accessed through the local network? It doesn't need to interfere with the data collection or the encryption, you are just allowing the user to access the device locally, before it is even encrypted to be sent to the servers.
To be honest if I am choosing between two devices and one supports HA and the other doesn't, the choice is quite obvious. I think one way to convince your higher ups is that you will be more appealing to a big niche of tech users that have elaborate IOT setups (which means $$$).