I subscribe to both OnX and Gaia. I find OnX works great with CarPlay and Gaia kinda stumbles a bit. I doubt AllTrails works with CarPlay or Android Auto.
I read somewhere that the transmission system has both heating and cooling. You might talk to a Toyota service guy about how this mod could affect warranty.
I read through the Reddit thread, and I think someone at Toyota misunderstood the question.
The app works through the truck's cell connection–thus the need for a subscription. The subscription pays for the truck's cell service.
The fob connects from a radio signal.