Would like to thank everyone (Jimmy07, Vincew58, etc) for the time and effort to research and develop this upgrade for everyone, especially the 19-20 owners and figuring out the slave BCM trick. The harness from Jimmyy07 is well built and protected so shouldnt have any issues once installed. I just got done with upgrading mine, it was pretty straightforward and took me about 1hr 20 min and I took my time to route and hide cables as clean as possible. Using the digital rear view mirror at first is a bit trippy and will take some getting used to, but the field of view is so much better than the conventional mirror. I highly recommend when you get all the parts is to bench test connected to the truck before truly installing it. I got kind of concerned at first when I didnt see anything but it does take a little time for the screen to turn on.
I have some tips for the install mainly for those with Forward Collision Warning and panoramic sunroofs. 10 foot fakra cable (i personally bought the 10' one from pasternac) maybe a tad short depending where you want to run it. 10 foot was fine for routing along the headliner and weather stripping to the rear of the cab, then to the guard where the rear window slides and then to the CHMSL. It will not be long enough if you try to route this through the passenger side instead because of the fakra connectors favoring the drivers side on both ends. If you really want it on the passenger side whatever reason I would get a 12 foot to be safe. For those without the panoramic sunroof or any sunroof you can run a more direct route with the fakra cable and 10 foot is more than enough.
As for the mirror bezel for those with FCW, the first thing you want to do is remove the small cover thats in the center, at the the base of the mirror stalk and goes to the headliner. Just use a pick at the top and it pops off easily. The main bezel is held on by 4 pretty aggressive clips. You want to start at the passenger side lower corner, youll see a notch where you can insert a plastic interior pry tool. Start there and pry it off. The remaining 3 can pop off with just you pulling with a decent amount of force. I watched a video online where the guy used a tool to pry it off and it cracked the windshield (they were replacing the windshield anyways in the video) and it made me paranoid. After you installed and verified everything works, now to put the surround back dont just go cranking the bezel, you can break the tabs which are fixed to the windshield or break the socket the clips go into. For me at least, I had to remove those 4 clips from the bezel, bend back some of the spikes (prevents you from installing the bezel), and put the clips back on the tabs on the windshield. Then you can take the bezel and it snaps in easy. If you just went and cranked it, the spikes would prevent it from seating and you'll be breaking something.
For stashing the slave BCM (I bought a used 22 one off ebay), I put it in this cubby area thats above and right of the gas pedal and hid the harness under the carpet for now. The factory BCM is directly opposite of this spot in the drivers foot well if you were curious . Initially, I was thinking of putting it in the space thats behind the steering shaft where another module is mounted, double siding taping it on top of that module, but but it didnt seem to fit cleanly. Another option is under the drivers seat, even at the lowest setting it wont crush the BCM or connectors.