Getting started: raspberry pi or Nas? Ikea Gateway with Xiaomi zigbee devices?

Hi everyone, I was intentioned to buy a raspberry pi 3 to use that as hub for home assistant, but I thought maybe I could be able to use my Western Digital Nas as Hub, that’s right? In my idea, the project should involve my smart products by Ikea, Yeelight, Xiaomi and Broadlink, at the beginning, with Amazon echo as main input control. Can I use my Ikea Tradfri zigbee gateway to control other Zigbee devices (I’m interested in Xiaomi sensors/buttons)? Thank you everybody for your help!

Ikea gateway doesn’t support Xiaomi sensors, Xiaomi gateway supports Ikea devices since recently. Other solutions would be to go to a 3rd party gateway like deCONZ or zigbee2mqtt

Thank you very much!
For example, I found a cheap Zigbee stick on Aliexpress (zigbee cc2531). Could be fine to control every zigbee devices? I’m totally noob in this topic, but I read about different kind of zigbee devices (es. digizigbee, ecc.). I’m searching for the best all in one solution at a good value for money.

I can’t really say. I only use deconz.