It would be more of a hybrid of those two methods. You print the large parts (even a micron is "large") into place, then let the cells grow the small connection

It would be more of a hybrid of those two methods. You print the large parts (even a micron is "large") into place, then let the cells grow the small connections we cannot reliably engineer, like planting a garden. All this reminds me of that classic statement about human longevity and the lack of spare parts.