We have a wifi booster and cell phone booster built in. Radar/speed detector would be wasted on us as we do not speed in our B. Our radio GPS is very effective in letting us know visually and verbally when we go over the speed limit. I find speeding uncomfortable to and hard to do for that matter. What we do have is a built in dash Pioneer radio receiver that does everything - backup camera, GPS, DVD, AppRadio, Internet radio, Sirius, TV, and who knows what else. I even saw one setup where there were cameras all four sides of the van that could produce a realtime composite plan of the vans surroundings. I don't have that.
I use my iPhone as a dash cam or photo taker. Sometimes I put it in a holder and connect up the earphone cord. The earphone volume control will snap photos. I did a lot of that going to Alaska to catch wild animals on the road. I missed the moose that jumped across our path. It startled me.
I use my iPhone camera more and more instead of a regular camera because the quality is good enough, I can do post processing with many apps and I have immediate access to social media without going through steps to get a photo there. It is way much more convenient.