I got the Kenwood DNX775RVS last year from Crutchfield. They offer harnesses and faceplate kits based on your rig and it fit my 2015 Roadtrek Adventurous RS fine. The unit has Garmin maps and is Sirius "ready." I also got the SXV300V1 Tuner from them.
Everything worked (backup camera, speaker hook ups, GPS, etc) except the MB microphone. For that we had to install the separate mic which comes with the Kenwood.
I specifically wanted a unit with built in NAV and didn't want Apple/Android Car apps. And I wanted a unit that was compatible with Sirius. Also, I wanted a non-Chinese company. I would have preferred a larger display as this one is only marginally bigger that the MB stock unit. However, the only way to go bigger, and meet my other wants, would be to get a "floating" display which extends out through the dash.
This unit is pricey but it game me everything I wanted except the larger display.