Integration for german smartmeter (CONNEXA 3.0 - Theben)

Hello everyone,

the problems with Conexa from Theben have not left me in peace in the last few days. A small note at the end of the LOGS gave me an idea. It said that the transfer of the attributes was limited to 255 characters and was therefore truncated. The idea now is to try as described in
Integration with Gardena Smart Sileno mowers, by using sensors
, i.e. with sensors and with template sensors in the configuration.yaml. Here is the code for the sensor:

sensor:
# Get Theben Conexa SMGW ID
  - Name: theben_conexa_smgw_id
    platform: rest
    resource: https://192.168.XXX.XXX:443/smgw/m2m/<userID>.sm/json #Die UserID was fetched via TruDi
    method: POST
    scan_interval: 900 # query every 15 minutes
    verify_ssl: false # SMGW uses a self-signed certificate
    authentication: digest # Enable digest auth
    username: "<username>" # as communicated by the carrier
    password: "<Password>" # as communicated by the carrier
    Header:
      Content-Type: application/json
    payload: '{"method": "smgw-info"}'
    json_attributes:
      - SMGW-Info
    value_template: 'ok' # only this string is decisive here, no retrieval of values.

Now the template-sensor is used:

Template:
  -sensor:
     - name: "SMGW Firmware Version"
        unique_id: smgw_firmware_version
        state: "{{ states.sensor.theben_conexa_smgw_id.attributes.get('smgw-info', {}).get('firmware-info', {}).get('version', 'Unknown') }}"

Voila:

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Do you think we can make progress on this path?