I own the 2016 version. It works well but I have two complaints. The mount is not robust and since I started using the Nyon, I no longer need the Garmin computer that also displayed the Varia’s output to the side. There appears to be no way of purchasing the unit’s display without purchasing another detector. Pass.
It won’t give you images of what is behind you, just moving dots which represent vehicles.
If you don't already have a GoPro (or the OSMO pocket action cam, which is great), one of those would work.
Alternatively, there are motorcycle specific options that come with roughtly 3" display, and two cameras (front and rear) and can be powered by a USB battery.
I think a possible inexpensive option you can try is using a wired inspection cam/endo/boroscope. That can plug directly into your phone.(OTG compatible)