Update:
I just purchased a renewed unlocked Pixel 4a from Amazon, as it was the smallest phone currently available to run GrapheneOS. The 4a is my current phone as well as I appreciate it smaller dimensions. The Web Installer was just a joy to use and warrants yet another donation to the GrapheneOS team. I'm also going to drop a note and ask them to consider a future device aimed at kids, i.e., GraphenOS loaded into a small device. The size of the Jelly phone from Unihertz seems ideal. Link: https://www.unihertz.com/products/jelly-2
For an eleven year old, the phone is still a bit of a brick to carry around. He agreed that the phone would be off and kept in his backpack and to be utilized for contacting parents when needed.
A big thank you to the team for coding up, what I think, is the best mobile phone OS for kids.