Just wanted to share my install story in a 2019 Rabbit Edition as this car has the all in one head unit which people haven't talked about too in depth.
The install is mostly as usual but I found it helpful to take off all the side glove compartment plastic trim pieces. There is a nice convenient channel above those plastic parts behind the glovebox to lay the cable.
Take off the HVAC trim by prying up the bottom and then work your way around the head unit plastic trim with some tools. I don't really know a great way to do this and there is a mix of plastic and metal clips to worry about. Take your time and remember that the entire vent assembly comes out with it. Don't lose a metal clip in the vents!
You need 4 VW keys to get the touchscreen out and its helpful just to remove all radio cables and set it aside. Snake the helix cable through best you can and wire accordingly. The head unit connector is exactly the same as previous guides, I promise all the connectors will fit behind that thing!
The plastic that connects the seatbelt slot halves together is a real pain to snap back together, you're better off lifting the whole lower trim up and off to work on it in a good position.
There is a 10mm bolt that holds one of the rear trim pieces to the rear seats and the cable kind of runs right over it. I just put a tessa tape bandaid where it rubs and dealt with it.
Hard reset error codes is when this gets fun. Almost everything cleared as soon as I moved the car but I had a persistent airbag warning and the fuel level was reading dead 0%.
For airbag VCDS showed "passenger airbag light open or short to ground". That happened because I tested the radio with power while not having the passenger airbag light cables connected.
The fuel level was odd to me, but I couldn't remember my starting fuel level for the life of me. VCDS was showing some weird levels but everything seemed fine. I ended up reseating the fuel level sending unit connector under the rear seat. That at least made the needle move a little bit. I filled up the tank and realized I needed gas anyway, but that needle flatline was bugging me!
Also of note I took the DSP apart to look at the board and measure some things. If this board is what I think it might be and based off the Audiotec Fischer PP 62DSP with all the cool ports taken off. The knob everyone is talking about as subwoofer gain may actually be speaker level voltage input sensitivity adjustment. I didn't measure the speaker level voltage when I did my install, but if that is accurate I wouldn't mess with it too much. Personally I felt programming DSP file 57 made a big difference.
Sorry for the long post but hopefully this is helpful. These are all things I had questions on and wanted to put them in one place.
Only took a few hours even with the troubleshooting! Happy listening!
https://i.imgur.com/iPXTnMg.png