Based on my research, there's a couple of different paths. One is to buy a Chinese third-party box that you plug into the head unit and cram into whatever space you can find behind your dash. It has most of the functionality, but has some limitations. I didn't go very far down that rabbit hole because the whole process didn't interest me. I believe one of the limitations is that it's essentially taking over your AUX input, so you can't have multiple "channels" of audio at the same time (like being able to listen to your radio while also having a phone input for turn-by-turn). It's possible I'm mistaken on that, but trying to deal with an extra piece of hardware in an already tight space just wasn't what I wanted.

Another method is to pay one of several outfits that have essentially ripped ID6 out of a car and they then install it in an ID4 vehicle. You have to check your software version to make sure the car is compatible (if it isn't, a third option is buying a whole new head unit brain, but that's more expensive), but I'm guessing yours would be since you bought yours around the same time as I did. The process requires you buying a WiFi antenna and a OBD to USB cable. Also having a battery charger that can keep up with the electrical drain. The process takes an hour and you have to have a computer (laptop recommended) at your car to plug in the OBD cable to. This is how the data is transferred. You can also just start the car and leave it running to keep the battery charged. Once the process starts, the car is unresponsive for the process and pretty much everything turns on. You can still manage the manual portion of the HVAC (AC and fan), but that's it. A tech will tunnel into your laptop with some software and basically controls your laptop to do the install. It's a program similar to what the phone scammers use in India. I just made a separate Windows account for the install, but I watched the whole process and there wasn't anything nefarious going on. You can delete the program once they're done.

You also have to pop the dash off and get to the back of the head unit to install the WiFi antenna. It's actually a pretty quick process. They say it takes 15 minutes, but it took me ~45 minutes because I had a couple of plastic clips that were stubborn and I didn't want to snap them off. Putting it back together takes 3 minutes. You can buy an OEM antenna (what I did, as it was a little smaller) or you can buy a third party off of Amazon. The antenna sits in a cavity underneath the head unit.

And that's it. You have wireless (only) CarPlay, but your USB port will still charge (and act as a USB device for media/transfer to the onboard DVR). I think you might also have video playback on the screen, but I haven't messed with that. Like I mentioned, the only real issue I had is that I can't hear Waze or iMessage/Text notifications, but I haven't really trouble-shot it much other than checking the various input volumes in the car's settings.

More to follow on the 4Runner discussion...work calls.