Build a pc starter

Hello I would like a device that connects to my pc system connector and then connects to the motherboards system connector. The device will be Bluetooth and connect to Alexa so I can turn it on wirelessly but I still want to be able to press the button on my pc to turn it on. I don’t know how power will work and please make it small to fit in my pc. I have a Lian li lancool 2 to give you an idea of the space I have