Earlier quoted context omitted.
HomeKit is not open and requires Apple devices.
That is not true. The HomeKit protocol is documented. There are at least a few open source projects that implement it both as accessories and hubs. Home Bridge being the best known one. If all the accessory vendors were to go under and Apple were to stop supporting HomeKit tomorrow, HomeKit accessories and hubs would still operate just fine and alternatives could be created. Even using Alexa or Google Nest for voice…
From what I can tell, Homebridge implements Homekit as a device, receiving commands. But can anyone build an app or device to send commands, outside of iOS?
The fact that I can't find an Homekit control app for Android strongly indicates this is not possible.