Thanks for the JSON file @jmarandet !
I do indeed see some Matter clusters not managed by Gladys:
"id": "156",
"name": "PowerTopology",
"id": "144",
"name": "ElectricalPowerMeasurement",
"id": "145",
"name": "ElectricalEnergyMeasurement",
I’ve created a feature request to keep track of your request:
Even before talking about Gladys, I think you need to make sure everything works on the Shelly side.
Have you tried on your computer software like MQTTX that let you view the messages published to an MQTT broker?
The first step to get unstuck is to see where your Shelly is publishing!