Hi,
I have worked on Firebase Realtime Database and it's other tools, Node.js, python, sql, and front-end to develop an environmental monitoring and control system for a hydroponic farm at a local facility. I, however, met my need in a different configuration.
You're configuration is more stable and I can add to the reliability and stability of you already designed project.
My estimated cost on your generalized requirements is EUR 700, for a contact period of 30 days.
I can start with your next step and I am available to work right away. I have Arduino, Raspberry Pi, SIM900 module, GPS, linux machines, MacBook, and most of basic electronic tools and equipments.
Looking forward to work with you.
Thanks,
Naeem