1. Please kindly refer my comments as below for your concerns:
- Can the CCG2 act as an endpoint and negotiate the PDO (9V@3A) with the Apple PSU by itself ?
>> Yes, CCG2 can do it after you added 9V@3A into sink PDO.
- If the answer is positive, is that easy to program the CCG2 to behave as described above using the EZ-PD Configuration Utility ?
>> Yes. It is easy to programming the CCG2 using the EZ-PD Configuration Utility via I2C bootloadering.
2. Can you please comment and let me know if the solution suggested above makes sense for my application ?
1) For hardware design, we could like to recommend you take a look CY4521 schematic, which is DRP and data source design, for your project, you just need keep consumer path is okay.
2) For firmware design, we could like to recommend you install EZ-PD configuration Utility, CCGx SDK, and go through the user guide of this two tools. And begin firmware customize (just for GPIOs, I2C,...) based on your requirements.
3) For programming, CYPD2122 (all of part number could get from Order Information of datasheet) can support SWD programming and I2C bootloadering.