I'ii repeat the following:
Points of Interest (POI) and Speed Cams:
Nissan Head Units upto 2017 (Connect 3) have a Nav menu entry for POI's. Those can be two files of either your own places or a full library of UK/EU Speed Cam positions. The French have a nasty ban on Speed Cam detection.
I don't have the latest Connect head unit that incorporates Android Auto/CarPlay. So, I don't know if the Nav system has a menu entry point for POIs. Can somebody have a look because info is scarce....and report back please.
Other than that there is an Android App that will present Speed Cams on Smartphones as mapped POI's with warnings. It requires an annual subscription. Its original intention is as a database for all common GPS Navigators and some cars.
https://www.pocketgpsworld.com/modules.php?name=Cameras
As regards plugging stuff into USB on these lame head units my guess is that the unit being plugged in takes priority...dunno.