For the UFP design could use low cost IC BCR CYPD3177, it is support PD3.0 function and have BCR HPI (Same as I2C) port which can accessible for PD contract voltage and current. The schematic is on the website: https://www.cypress.com/CY4533
If you want to write the PD firmware by yourselves, below chip you can select:
1. CCG3PA: CYPD3171. The schematic is CY4532 kit:https://www.cypress.com/documentation/development-kitsboards/cy4532-ez-pd-ccg3pa-evaluation-kit
2. CCG4: CYPD4126 (There are no existing schematic can be refer to, but you can refer the datasheet.)
3. CCG3: CYPD3120/CYPD3123/CYPD3121 (You can refer C to DP reference design and remove DP interface. Link: https://www.cypress.com/documentation/reference-designs/ez-pd-ccg3-usb-type-c-displayport-cable-solution )
Thank you very much.
One more question. I also want to connect CCGx device to PC over USB 2.0. To my understanding CCG3 supports USB2.0 but only for Billboard device class? Does it also supports just "normal" serial port bridge over USB 2.0?
CCG3 have capabilities to support serial port bridge over USB2.0 and it (USB2.0 to I2C) is implemented in the CCG3 C to DP firmware, you can refer to it. For other class, you need implement it in the firmware.