I could be wrong, but being able to control the audio with the steering wheel could just mean controlling the bluetook audio. No signal processing needed for that.
I assume you meant fires and not tires.. I have my charger in the garage, no issue. The Rivian battery is sealed and has a decent amount of fire retardant around the cells.
I'm not worried in the slightest.
What we really want is a DC charger for the truck that takes the current power generation from solar and does the typical voltage adjustment (reduce amp, up voltage) to be able to charge the truck with whatever level of power being generated.