physical books are a greate idea.
I do something similar but with email and more pro-active [1]. I have created my son an email address when he was born and I'm sending him things from our lives and ask family members to to the same. Just to write them about themselves and send photos of their current homes and gardens and partners.
I imagining him looking through his email when he's 18 and reading personalize messages sent by family members who might no longer be with us then.
[1] https://blog.haschek.at/2024/leaving-a-digital-legacy.html