Zigbee Integration

I want to integrate Zigbee into Home Assistant so that I can control my Phillips Hue lights. I read https://www.home-assistant.io/integrations/zha but I’m wondering if a USB is required in order to get this to work? Is there any way to do it without ordering more hardware? I also have an Echo Plus and was wondering if there is any way to use that as a bridge for Home Assistant. Is it possible to have another hub integrated with Home Assistant?

How do you control your Hue lights at the moment ?

I control the Hue lights currently via Alexa voice assistant and also via the Alexa app.

You use the Echo Plus as zigbee coordinator ? I did not know it was possible.

Yes, the Echo Plus supports Zigbee.