Awesome! I knew by commenting someone educated would come along. Thank you very much.

And they're using recommendations from the USB consortium, which is comprised of all the large manufacturers in the world, so it should always be up to date during the review process.

Manufacturers are allowed to add supplementary charging standards on top of USB-C PD

Controversial opinion: I wish this wasn't the case. So many different proprietary protocols, most of the time you'll still need a specific adapter, and in some cases even a proprietary cable to utilize the full speed, and nowadays most devices come without the adapter.
And there's even PPS in the PD spec allowing to request for a specific voltage rather than something in an existing list.

But I do also have some personal grievances here:

1. Mi TurboCharge - This may be something based on PD, but still being something separate. I don't know, but I do know it requires more pins than USB-A has. 5 pins. Somewhere I read this is connected to a CC pin in the USB-C connector. But no, they did not use USB-C, they used USB-A, with an extra pin. Only shortly before the phone died I finally figured out why it wasn't charging as fast as expected - I wasn't using their proprietary cable.

2. My current phone's interference (?) with Qualcomm QC 2.0 - Somehow when using a cable with non-perfect connection on QC-compatible adapters, when I move the USB-A connector, it starts triggering 12V mode until it finally shows overvoltage error and slows down to 7W. QC 2.0 is how my USB tester identifies it. This is a MediaTek-based device, so I don't think it would support QC. The original adapter uses PD and some 11V 6A thing with unknown protocol. Perhaps that is where the problem originates, I don't know what data it sends down. But testing with OTG adapter on the original brick it seems the protocol needs the extra pins of USB-C to work properly.

I've had 3 phones that supported some fast charging, so far 2 of them made it into a confusing mess. Had they all used just PD it would have been a better experience.