I did sketch out a slightly more 'professionalised' version, but haven't built it yet https://github.com/samuk/IoT-Greenhouse-Temperature-and-Irri...
I'd be pleasantly surprised if DJI had done anything open source, Ardupilot is pretty capable of course. I really want to automate the time consuming labour parts of horticulture, for me that's mostly weeding and to a lesser extent harvesting.