The easiest by far solution is to simply copy them forward to new media once every year. Have an offsite copy.
I don't trust any cloud backup. They can go dark at any time for any reason, you can lose your password, you can get "canceled", a hacker can ransomware it, etc.
I periodically check that ransomware hasn't infected my backups by seeing if an unrelated device, like a media server box, can read the files on it.
I have no faith in "archival quality" media, as if you can't find a device to read it, it's worthless. Have you noticed that computers increasingly don't come with CD drives anymore? Why would anyone want them, since a 64Gb USB stick goes for $6? Soon there will be no way to read those "archival quality" CDs.
I don't expect my children to be able to explore my digital archives when I'm dead in 50 years or so, so anything I want to be found then I print or otherwise place on a physical medium that's readable without computers. The less important stuff can stay archived on hard disks as plain files on a FAT32 filesystem. With a physical label on the disk describing the contents.
The key is in the curation though, it is unlikely that your child will want to sort through thousands of blurry, duplicate, or unrelated photos. 100 really good and special photos/videos are better than a mixed up mass of 5,000.
If you are concerned with passing away before your son is of age, just make sure there are multiple backups, and the sign in information for anything that isn't local is communicated to his guardian.
My advice would be to cut selected items to an SSD on a routine basis and either stash it in the family safe or wherever you keep important files. Use an existing filesystem, not whatever the latest newfangled vendor specific one, and use a fairly well documented format for images. Store documents as text or rtf.
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.
Homelab runs photoprism (open source google photos alternative), plex, code-server, etc.
[0]: https://icedrive.net
We can iterate from there. Wouldnt it be sweet to be able to let other people dump more credit into your provider wallet, so it could keep going? Maybe we could standardize a "end of service" webhook/notification, and your website & content could jump ship & re-instamce itself on another provider automatically if your current one declares it's going under.
Dont forget to setup after-life DNS too!
Then I have two 5TB LaCie Rugged drives that I just attach to the Mac. Finally, using ChronoSync to schedule copying contents from the Mac to both drives as mirrors.
However, for the digital content I have published, such as our podcast, I plan to form and fund some sort of trust that will be tasked with keeping it online and publicly available for as long as possible. This may just mean making sure it is archived in at least one library, the Internet Archive, etc.
When some interesting thing happens with the kids, I shoot an email to their accounts in which I write the conversation, the way I felt, how we admired what they did, what we learnt from them and such things.
Photos: I will manually copy the photos from the drone and DSLR to the nas and format the TF card after copying.
Phone photos: I use the software provided by my nas service provider to back up my photos
Web pages: I run my own docker version hamsterbase on nas. Store all the pages I am interested in.
There are also M-DISC disks and drives (archival quality BluRay with some specialized layers chemistry). Since they are positioned for long-term archival, I expect there will be some need to read them in the future, so some sort of drives will remain available.
But Online storage must be encrypted. So the question is, what backup or encryption software do you use to be able to decrypt the data in 10—15 years or so?
2. I back up locally to a drive inside a firebox (w/ built-in usb connector)
3. Backup offsite encrypted to Backblaze b2
Format: a simple folder tree /Pictures/YYYY/YYYY-MM-DD-Album-name