Chosen Solution

I have an icloud locked 128GB motherboard of iphone7 and a working 32GB iphone7, is it possible to swap the 128GB NAND flash memory to working phone?

It is technically possible, but it requires extensive work to transplant the chips and reprogram the board data. It is not DIY level operation and not economically feasible unless you plan to open a specialized business for it.

There is no separate hard drive in an iPhone. Everything is integrated into the logic board.