Some meters have a so called Master or default key, like the iPerl or Sensus meters:
Maybe try to figure out if your model has that as well. Unfortunately the water and gas metering not regulated as far as I know. Each company implements whatever they want. There is no standard requirement. Mine has a Cyble AnyQuest, not wmbus, and screws up the software of the water company if I start to read it. Allegedly they cannot read it anymore… Ooopppsss… (Lack of understanding of the meter, the software and the equipment all together…)
You can also do differently with the ESPHome device, you can use it to transmit the telegrams to the wmbus addon to do the decryption there. There are some discrepancies between the ESPHome reading and using a dedicated RTL SDR connected to a PC/RPi which can improve reception too.
To identify correctly that the meter transmits I would also use the RTL SDR, as the electricity meter should output wmbus telegrams continuously, every minute or every 15 seconds, or whatever is defined in the regulation.