Why do you think DC to DC fast charging will be better than AC to DC fast charging? Both involve voltage conversion and the conversion has about the same efficiency. The one advantage is that could choose higher DC voltage, like 480V, and send more power on same wires. But that won't get you DC fast charging, will still take a couple hours to charge.
A lot of the things you are talking about will require conversion. LEDs will still need conversion from line voltage. Any incandescent lights will need AC conversion. The USB-C adapter will still exist, and there would no effect on charging speeds.
You can get most of the benefit by having DC power cables between the battery, solar panels, and inverter.
Most certainly DC to DC is faster. It is only limited by the local infrastructure. i.e. want to charge faster? own a bigger / better battery bank, with bigger charging cables and a better car.
DC -> DC (with some PWM / battery management) can also be slowed down (or use reduced amps) to best suit the moment. So if versatility is better, then DC to DC is again "better".
This is the scaled up equivalent of an external laptop AC/DC power brick. It’s faster because it’s supplying much, much more power. Multiple homes worth.
Batteries need DC to charge and putting the transformer in the external fast charger means the one in the car itself only needs to be sized for lower power domestic charging.
A lot of the things you are talking about will require conversion. LEDs will still need conversion from line voltage. Any incandescent lights will need AC conversion. The USB-C adapter will still exist, and there would no effect on charging speeds.
You can get most of the benefit by having DC power cables between the battery, solar panels, and inverter.