HomeKit integration was a main driver for me to choose tado. I don't like being dependent on cloud services for things that are practically local to my house, so I have configured HomeAssistant to use it through the HomeKit integration.
However, after installing it, I found out that there is an important feature that is not supported through HomeKit: the hot water temperature. I can set a temperature through the cloud (including on a schedule, or using the tado home/away setting, but both of those are cloud-only as well). If the tado is not connected to the cloud, it will keep the hot water temperature at whatever it was last set to when there was a cloud connection.
This is not an acceptable limitation to me, and it shouldn't be that hard to expose this setting through the HomeKit integration.