Hi Sir,
I have understood your requirements and you just found the right guy. I am a part time android kotlin developer buy I am an electronics engineer by profession. I have great experiences in building IoT based systems especially home automation. Just recently I created an IoT based plant monitoring system using esp and rpi and included modules such as peltier, rtd, temperature sensor, growth light, level sensor, pump, etc. I also created an android kotlin app to control and monitor it. I used firebase as database. Im also an expert at microcontroller programming. Contact me for more details and to see the works I have done. Can't wait to work with you!