Android/iOS - Bluetooth communication using app as a service?

Question

Android

Good day
An idea arose, perhaps on its basis then something will grow more serious. We need advice from knowledgeable people about the fundamental possibility of its implementation in modern conditions.
The idea is to create an application for Android / iOS phones, which, in service mode, listens to surrounding Bluetooth devices and, if it finds one with a certain identifier, then starts communicating with it at certain intervals.
An example is this: I want that when I enter a room with a phone in my pocket, the light will automatically turn on in it if it is already dark outside.
Those. in the room there is a certain Bluetooth sensor connected to the computer, when I approach it, the phone starts to see it, by increasing the signal level we determine that I am approaching and after reaching a certain level, turn on the light (how to do this is another question).
I would like to use Bluetooth as an example of a common sensor. With an eye to the future, the possible development of an idea into a project.
And another question. If I suddenly want to put such a sensor in the bathroom, but the same central computer must process its data. Is it possible to somehow combine Bluetooth with WiFi in one small sensor / device so that it already communicates with the central computer via WiFi?
Thanks in advance

Answer 1

Both bluetooth and Wi-Fi drain the battery a lot, the idea is not alive, connect the sensor to the cotton, turn it off, it's also convenient and simple.
Determining the distance by signal strength is also a myth due to obstacles.