If you're ready to share all that, and it's just family photos&videos (nothing too sensitive that you won't mind them leaking through ordinary bad security and social media), then you could give them access as soon as they have their own online accounts, and they could just grow up always accessing it.
But, for financial/estate data that my heirs might eventually needed, I have a script that `rsync`s select data to (multiple copies of) an unencrypted external USB drive, in FAT32 format.
Included on the drives, and also stored printed with them, is a one-page `READ-THIS-FIRST.txt` file that says what info is on the drive, as well as top-level summary about other things they might need to know (like what insurances I have, any will, and how to access the GnuCash files).
There's also a PDF&paper one-pager assets&liabilities report from GnuCash, for use before anyone gets around to installing GnuCash. This enumerates all the accounts where money is stored or owed, and sets expectations for the reader's very-very tiny inheritance.
There's also passwords. Mine are currently handwritten in a redundant pair of Rite In The Rain paper notebooks, one off-site. But you could also use a password manager service, and some services can release more passwords to family members upon your expiration. Your survivors being able to just one of those accounts, might save them a lot of headache, and you don't know which one that will be.
Even for only family photos that they can already access, you even might want to have a one-pager bus-factor document that includes things like how to keep the photos from disappearing (such as by not getting locked out of access, not failing to pay a cloud service bill, or not donating the old junk servers that were storing them). If this one-pager is accessible to kids, maybe structure it as notes for yourself of how things are set up, like an engineering nerd, without alluding too much that they'll someday need to do it.