I'm trying to hard wire a Uniden R3 in my wife's 2021 RR to use with a mirror mount for the detector. There are two types of harnesses in general to do this:

1. Pull 12v from the rear view mirror by back probing a plug, or
2. Pull 12v from the fuse box.

Type 1: Since these cars have Homelink, they should have 12v power at one of the plugs in the mirror. So I pulled off the smaller plastic cover from the mirror and probed the only exposed plug but couldn't find 12v with the ignition set to ACC ON. I also tried removing the larger cover just above the mirror but couldn't get it off without physically taking the mirror off, and the two metal tabs that appeared to be holding it on seem like the kind that will snap from repeated bending, so I wasn't about to try that.

Type 2: I couldn't find a fuse box inside the passenger compartment. Is there one? So I removed the cover from the one in the engine bay directly behind the glove box but this time, I couldn't find a way to get a wire from the fuse box into the passenger compartment without going around the door jamb, which is not an option. However, I was looking from above the car. Perhaps it would be more apparent from below.

Given this, I have a few questions:
Regarding the rear view mirror, is there 12v power up there? If so, where? Would I have to remove the larger plastic cover to access it, and if so, how do I get the cover off? How can I remove the mirror?

Regarding type 2, is there a way to go from the fuse box through the firewall? If so, I could easily hide the wire by tucking it in various places (e.g. the headliner).

Now the easiest solution is a plug and play harness that will work with the factory harness, like is available for a lot of GM cars, for example, but I haven't been able to find one for the RR.