Hi Radu,
Sorry, I just saw your message.
I’ve managed to integrate the A3 into HA locally, using, in the configuration.yaml, the following code:

sensor:
  - platform: rest
    resource: "http://<IP_Address>/j"
    scan_interval: 60
    name: uRad_Local_Multiple
    value_template: "OK"
    json_attributes:
      - data
  #    json_attributes_path: $.[0]

  - platform: template
    sensors:
      urad_temperature_local:
        value_template: "{{ state_attr('sensor.urad_local_multiple', 'data')['temperature'] }}"
        device_class: temperature
        unit_of_measurement: "°C"
        friendly_name: uRAD_Temperature_local

The first part extracts the values in json format from the A3, the resulting entity looks like this:

data:
  id: 'xxxx'
  type: '82'
  temperature: 21.27
  humidity: 56.91
  pressure: 99716
  voc: 414758
  co2: 900
  ch2o: 46
  o3: 0
  pm1: 114
  pm25: 143
  pm10: 189
  noise: 77.94
  uptime: 6497
friendly_name: uRad_Local_Multiple

The “- platform: template” lines are used to extract each value for Temp, Hum etc from the above output

Hope this helps