It's likely that you don't have to simulate even a single cell at high resolution to be able to simulate how an organism would grow. There are numerical shortcuts.

For example today we can already predict the color of the eyes and other phenotype from the DNA.

If you are able to observe enough samples of cell growth and their associated DNA, you probably can model and predict the statistics of a cell from their DNA. Because the cell is itself the result of a lot of chemical processes, the law of large number will help smooth those statistics.

Given that we have a lot of cells, the collective behavior is probably entirely governed by these statistics.