But the Pixel supports USB power delivery that does rapid charge by sending more than 5V (9V to be exact) based on the charger it comes with, 9V by 2A for 18W. I'm sure it's done differently than Quick Charge however and not interchangeable.
Correct. PD 2.0 is a separate standard, but is fully backwards compliant with USB-C.
Neither work with Quick Charge or turbo Charge or Samsung Fast Charge
For the record, I'm not sure i trust PD anymore than I trust Quick Charge. The connector body and wire gauges used weren't designed to use that high current or voltage. But trusting the people who developed and designed the standard is probably safe and I'm just too cautious.