According to the materials I've seen on the Internet, the final version of the Nvidia GPU is not what was planned, and it was ordered in a hurry.They were also supposed to have two CELL "CPUs" and no nvidia GPU... but that obviously did not happen as it seems the CELL was messy to develop.
They were planning their own solution, and it was likely to be a second chip on the CELL-based, or something else.
MS at the time ruined the game for everyone because they wanted to gain a time advantage, despite the fact that their hardware could not work well, until the new revisions were released in 2007.
There were even stories at the level of reliability "my Japanese stepfather worked for Sony" that the PS3 was supposed to launch in late 2007, or even later.