Projeto Iot Com Esp32 Para comercial

I'll try to summarize as much as possible what I want and if you have any questions just ask me.

I would like to develop a hardware, basically I want to create a gas sensor using an Esp32. This would be the first part of the project, the second would be just an app to visualize this data, alerts in case of leakage, that would be very simple.

But the challenge that I want and I want to solve is precisely to make it commercial, for example: To be able to develop a system that is multi-user, where the customer who buys my gas alert system can register this sensor in the app and have access the aforementioned information.

Summarizing what it would be: Develop pcb for this gas sensor system, app for the customer to register the device and the "backend" so that this idea of ​​several users on the platform works, so that they can see their registered devices, do you understand?

Then I would like to know how much on average you would charge for this and also the technologies that will be used.