> They only have very reduced schematics published, but it looks like the RPi4 isn't deploying a PD solution at all. I think they are just relying on the analog signaling of Type-C. The power supply is just a "simple" type-c 5V/3A unit.

This is the first I've heard of the RPi 4 not having PD -- could you point me to the specs you saw? I searched around a bit but couldn't find anything either way.