You can add devices with the HA community app just fine, but you’d read a bit more app info / push a bit more buttons before giving up imho 
Example
While a Mi flora is a sensor, you should add a sensor:
I pick moisture as device sensor:
After the device is added, go to the devices’ advanced settings
And for importing the rest of the devices’ entities, just enable both sensor options
(when a device should have switches and buttons, enable the 3rd & 4th options as well)
Voila, all entities are here now
https://community.homey.app/t/tutorial-pro-how-to-integrate-home-assistant-with-homey/92641
