The short answer for most people is the RCD330+ or the newer RCD340 like this one:
VW 6.5" Original MIB RCD340 Android Auto CarPlay Stereo 6RD 035 187 B - Version B
Direct fit with minimal effort and you can use a camera. There are other cheaper options for the same unit (or the one that doesn't do Android Auto) from Aliexpress if you want to go down that path.
Personally I'm currently looking at replacing the headunit in our Multivan (which is the same RNS/RCD as the rest of the VWs) with a headunit capable of wireless carplay as an upgrade from the current one that does wired carplay. We have had a couple of different Pioneer headunits and I'm looking at another Pioneer. You need a mounting kit and a wiring harness (if you don't want to cut up the stock wires) but it's almost as easy to install as the stock radios.
EDIT: This is the one I'm looking at for the Van: DMH-Z6350BT - Pioneer
When it comes to cameras, just make sure whatever you buy has the same connection as whatever head unit you get and it's all good.
Now if/when I upgrade the Van I might pass down that wired CarPlay unit to my Golf, although I will need a wiring harness, mounting kit and camera converter but on the upside I would also be getting a new Bluetooth connection rather than the stock one which is very much showing it's age at this point...
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