Hi. Swapping just the NAND chip won't work, as the data in encrypted using key material stored on the Titan chip. You need to swap the Titan chip too. I don't know how the hardware looks, and whether the Titan chip is a discrete component, but if it is, you may need to swap the CPU too, as the Titan chip may have a pre-authenticated encryption channel to the CPU, so one cannot just swap the CPU to subvert the security.
But I would be very surprised in the Titan chip is paired with anything else than the NAND chip and CPU, as no other component contribute at all to the data security. Just moving these component is equivalent to replace all components except these ones, which is of course fine from a security point of view.
So I think the swapping you want to do might work. But I am partially guessing based on how things usually is designed elsewhere. I don't know anything about Pixel hardware design or even phone hardware design specifically.