I can't imagine losing access to 18 years of life's history and memories because Google decided to kill free accounts, or charge more than you're comfortable paying, or they suffer catastrophic data loss. Or they decide to kill Workspace accounts and they can't be converted, and you are given the data in a mostly unusable format bc they weren't told how to export the data by the law.
I've lost entire wings of my mind palace because I lost a notebook, diary, hard drive, or published works and been bereft of that knowledge or those memories. Some wings I've been lucky enough to rebuild, others are like if the Notre Dame had never been visually captured, drawn, or scanned.
Imagine planning on recording 18 years of your infant's life--all their familial social connections and day-to-day happenstance; the things that make a person who they are--, preemptively, on Google's behalf. Then imagine not even having a guarantee that you will be able to use the data you collected for its originally intended purpose.
Set this up locally and in a format you control, and can secure yourself. Put it on a tape drive or on a USB in a digital storage preserver (something to power on the nand cells so they don't bit rot)
You don't know who your son is going to turn out to be. He might come to resent you for giving Google that level of insight into his life, or for recording it at all. After all, you have decided that your son does not have a right to privacy, and essentially given it away. Better to keep it local so it can be destroyed if that's what he would desire.