I actually did this just yesterday. I purchased an 8.4” VP4 Nav unit off of eBay for around $300. Bezels can be expensive (+/- $150) but it is simple plug and play, same connections as smaller unit. I switched because my original unit died. It took me less than 20 minutes to swap units. You will need a 911 override cable (911 Vehicle Phone Override Cable – Infotainment).I wanted to know if it is possible to upgrade my radio from the small 5in display to a 8.4in display with or with out navigation. I called a local parts dealer and they said it was not possible as they are different systems. I have watched a few YouTube videos where they do exactly this and go from the little display to the large one. So I am confused if it is possible or not.
I thought about an aftermarket unit but you need functionality of your climate control so I never pursued it.