Does HA need a zigbee adaptor like zigate?

Hello, I am currenlty using mi home with xiaomi aqara gateway, zigbee sensors & wireless relays.
If I start using HA instead of Mi Home, will I need to purchase a zigbee/zigate adaptor or will the Xiaomi gateway allow HA to communicate with the zigbee endpoints?

You can pair the Xiaomi Gateway with HA. But if you opt for a zigbee adapter like the Conbee, you have more choice in different devices from all kinds of brand you’ll be able to pair.

Yes you need a Zigbee Coordinator adapter if you want to use ZHA integration or Zigbee2MQTT, read:

https://www.home-assistant.io/integrations/zha

and

https://www.zigbee2mqtt.io/guide/adapters/

My recommendation as it stands today is to buy a CC2652P based USB adapter like ITead Sonoff Plus:

https://community.home-assistant.io/t/iteads-sonoff-zigbee-3-0-usb-dongle-plus-based-on-texas-instruments-cc2652p-20dbm-radio-mcu-now-sold-for-14-99/340705/

Regardless of the adapter you choose be sure to upgrade its firmware + use a USB extension cable, and plug into a USB 2.0 port or via a powered USB 2.0 hub and not a USB 3.0 port due to interference.

Thanks for your responses.
For the time being I only have xiaomi devices and all are working great via the Xiaomi Gateway with HA.
Do the adapters you have suggested in your thread (conbee & sonoff) universally compatible with all zigbee devices regardles of manufacturer?

Yes and no as it is complicated. Zigbee compatibility depends on a combination of Zigbee Coordinator stack/firmware, individual Zigbee device firmware, and Zigbee host application implementation. If and when individual Zigbee device firmware does not exactly follow the Zigbee specification standards as set by the Connectivity Standards Alliance (formerly known as the Zigbee Alliance) then the Zigbee application implementation will also specific converters (translators) to work around each device quirk and deviation for standard. You should really read the ZHA integration documentation, specifically this:

https://www.home-assistant.io/integrations/zha#knowing-which-devices-are-supported

and

https://www.home-assistant.io/integrations/zha#zha-exception-and-deviation-handling

Tips to prepare is to also read these tips so you know what to think about when set up Zigbee network:

https://github.com/zigpy/zigpy/wiki/General-tips-on-improving-Zigbee-network-range

It is really important to understand that Zigbee can be very susceptible to EMF/EMI/RMI interference.