How does bluetooth work in android?

Question

Android

I decided to write applications for using an android smartphone as a bluetooth adapter. Anyway, I decided to study programming as a hobby, but doing it aimlessly tedious. On the Internet, all applications that allow you to use a smartphone adapter transmit data via WiFi (!), So they write - for it to work, you need the PC and the smartphone to be on the same network. As I imagine it: An agent (with root rights) works in a smartphone, "intercepting" data from devices working via bluetooth, and transferring them via USB to an agent on a PC, which is visible in the system as a bluetooth adapter. The only problem is that I'm a form slap, and I can't even imagine how to formulate queries in Google. Yes, there is a lot to learn, but I'm not in a hurry. And the problem is that I ask "to give direction" What to read to start understanding how bluetooth works? About wasps in general? Specifically about android? How to work with bluetooth android?
(Yes, I know that dongles are on every corner, I had my own reasons for doing this)

Answer 1

Just for fun app
Bluetooth adapter for pc 0.5$
Application price in this case is not higher than 0.2$+VAT
if monetization of freemium installs/purchases = 0.5-2.0%
to earn 1$ it will take 250-1000 installations.
paid promotion disappears as a class.
Suppose for a year the application gained 100 thousand installations 25-100 $ minus 30%. Income 70%
If you were still able to put ads there. Yes, get much more.
But I have no idea where to put it in the background service.
For advertising outside the application interface, Google will be banned.
And it will take more than a year of work to write such an application.
In a year and a half I was able to implement in my printer driver
only 30% of what you need for your idea.
Immediately about USB-OTG. Not all models support it. It is not possible to
reliably programmatically determine that it is supported.
Root is not needed.
lebets.ru - to get started with bluetooth