Mqtt color xy brightness

Setup, Configuration and Use Scripts & Rules
3

You could use zigbee2mqtt’s “experimental” feature “attribute_and_json”. Then send commands for colorXY and brightness in two separate channels. This allows to use a dimmer channel for brightness, where you can set minimum and maximum value.
This is how I configured my lamp (Aldi brand):

UID: mqtt:topic:mqtt_raspberry:ZigbeeRGBLight01
label: ZigbeeRGBLight01
thingTypeUID: mqtt:topic
configuration: {}
bridgeUID: mqtt:systemBroker:mqtt_raspberry
location: Bedroom
channels:
  - id: power
    channelTypeUID: mqtt:switch
    label: Power
    description: ""
    configuration:
      commandTopic: zigbee2mqtt/ZigbeeRGBLight01/set
      stateTopic: zigbee2mqtt/ZigbeeRGBLight01/state
      off: OFF
      on: ON
  - id: dimmer
    channelTypeUID: mqtt:dimmer
    label: Brightness
    description: ""
    configuration:
      commandTopic: zigbee2mqtt/ZigbeeRGBLight01/set/brightness
      min: 0
      stateTopic: zigbee2mqtt/ZigbeeRGBLight01/brightness
      max: 254
  - id: color
    channelTypeUID: mqtt:color
    label: Color
    description: ""
    configuration:
      commandTopic: zigbee2mqtt/ZigbeeRGBLight01/set
      colorMode: XYY
      formatBeforePublish: '{"color":{"x": %1$s, "y": %2$s}}'
      stateTopic: zigbee2mqtt/ZigbeeRGBLight01

(Note: removed some channels from the code for brevity)