I did take a look at this. On Android there is no common programming interface for USB cameras. Implementation would require to use a 3rd party library which is known to cause problems on some Android devices and its license is not favorable for commercial app. And making such a library by ourselves is way too much work. So right now its not looking good for this feature.
I use an USB cam in my android phone (actívate by reversing light and relay) when the light IS on, close the circuit and automatically open the cam software even when i use RD. Exist Many apps for UVC cams. I vote for implement in RD.
P.D. the cam IS recicled web-cam from AN old laptop!
Basically you need one USB camera ( or make one… Laptop webcam for example, only need the webcam, 4 wires and USB conector) and mobile compatible with UVC (works in Samsung J6 2019 AND MI 9 SE). Software: program called “camera USB”.
When you instert the USB (with OTG adaptor) the program shows the image. It can use “mirror” Mode and invert the image.
To turn on the camera, i use 12v relay, Signal from rear light. When i engage reverse gear, close the circuit +5 v for the USB cable and automatically start the program!
I also vote for UVC support in Realdash, it is a standard driver included in Android by default and there are even many simple adapters for RCA cameras (Easycap usb adapters). With this you can connect even the normal reverse cameras, not only USB. All use UVC standard. It works on Windows as well.
Yes, even now you can set a trigger on reverse to launch the UVC app, but that will not be the same as creating a video gauge, displaying other details from RD in the same screen with the camera image. Or even an FLIR/IR camera showing at night as background for the dash (Mercedes/BMW style).
Why not use a non-USB camera? There are many car cameras systems on AliExpress compatible with Android.
Also, is should possible to overlay Realdash over an Android app. This is how TomTom overlays its own speed warning app data and audio over Google Maps. Of course, Realdash could overlay video imagery, sat nav maps, or any other apps by keeping Realdash in the foreground, and you can blank out anything you want that is in the background.