So it's based on Qualcomm Quick Charge? QC is a competing, slightly older, slightly simpler standard to USB-PD that can do what you described. It's...useful sometimes.

No, it’s not based on anything. A QC charger will output 5v by default and only increase the voltage after a negotiation. This is exactly as described: a USB-A style charger brick only it outputs 12v instead of 5v, no negotiation, nothing preventing you from plugging in a device expecting 5v and getting 12v. The only ‘safety feature’ is that it has ‘12V’ printed on it.

You can find it here: https://www.thermoworks.com/12volt-ac-adapter/