Not this one, but I have a handful of these GitHub - rbaron/b-parasite: 🌱💧 An open source DIY soil moisture sensor that works well. Plus you get light, air humidity and temperature in addition to soil moisture. A bit more DIY than your previous fireplace project though 
OH integration:
I’ve added some bluetooth support in the Esphome binding to proxy bluetooth traffic (see separate branch) as well as a new BTHome binding BTHome Binding [4.0.0.0;5.0.0.0) to parse the bparasite messages. Shelly BLU devices use the same protocol and are also supported.