This project took a somewhat unforeseen turn. I did not find a sensor matching my description without adding extra components to it. I'm sure that they exists but I found a more interesting way.
This weekend I have spent some time testing and learning new things and I love it! The result is a LoRaWan sensor meeting the demands above. At a very low cost I have the sensor.
I used a Raspberry Pi Pico, a SX1262 LoRa Chip module and some resistors. Soldered it to a PCB board and wrote some code. Still in the experimental phase and some things to add to reduce the battery consumption. My target is at least a year on battery. I also need a watertight case for it.
I'll probably tell more in the future. It's a hobby project so it will take some time.
Here is the current state (yes, I know the sticker with polarity is wrong :-))