Yes I did this, The Things Network takes the esp32 data, in which I use the lpp.addTemperature, lpp.addHumidity and etc methods … And I wanted a simple channel that I could modify on the Cayenne later. For example, add the lpp.addChannel method to esp32 and create a simple channel like the image from my first topic.
If you are trying to send something different than is already in the Cayenne LPP library then no, it is not possible. I tried to do this last week and consulted the forums at Cayenne also. No go.
Using the Cayenne MQTT API gives a lot more flexibility but one would have to create their own external process that receives the info from TTN and then talks to Cayenne directly.