Hello,
Thank you for reaching out!
Regarding MQTT options on RUT360, there are a few, depending on what protocol is used by the third-party device. If the device uses MODBUS TCP, it's possible to get the requested data via MQTT. A thing to keep in mind would be that the router will be acting as a MODBUS Master, as it will be pulling the data from a Slave device.
This Wiki article explains how to set this feature up, except Configuring RUT955 Modbus TCP Slave section can be skipped, as it's not needed when pulling information from a third-party device. The IP address should be of a third-party MODBUS device.
However, if the third-party device uses Modbus RTU (serial connection), a device with a serial connection will be needed. This can be RUT956/RUT955, TRB142, TRB145, TRB245, TRB255.
Let me know if there are any further questions!
Best regards,
DaumantasG