That would be another +1 from me for a MQTT subscriber as part of FarmOS sensors. Less specific to any particular physical network link.
Need to get a bit more familiar with Drupal again to make a better judgement. But there are some existing PHP libraries for this
https://github.com/mgdm/Mosquitto-PHP
https://github.com/bluerhinos/phpMQTT
These seem to be the most commonly used ones. I have used phpMQTT for some stuff in the past.

From a FarmOS perspective it would allow users to subscribe to any MQTT topic. It wouldn't matter if it comes via a LoraWAN network or some other sensor that can publish to MQTT.