How do I stream from external camera?


I have a big project, well advanced to create an app which will add a numeric dashboard on my old beetle. I am using an ARDUINO to collect data from sensors and to send them to the app through Bluetooth. The camera is to create a backward camera.
I tried to use a camera with FIFO chipset and to read and sent the pictures to the phone, but it is clearly not the solution (slow down the sensors reading as ARDUINO is not done for video and Bluetooth not adapted to such high data quantity.)
I think that the best idea would be to use an external camera (connected to the phone through BT, wifi, I don't know) and to stream directly the video on the app. But I do not know of it is even possible with MIT APP INVENTOR, or how to do it. I only found some ideas in the net with IP camera and streaming of a web page, but this is not adapted to my need.

Can you help me please ? Which type of camera would be possible to be used ? How to strem it on the app ?

Best regards,