So I've been doing more research on physical media, and I think the best way to go would be a data DVD with a downloadable version available for those who don't have optical drives anymore.
A DVD is very archival and USB drives are not. If a USB drive isn't plugged in regularly, its storage can degrade and corrupt, similar to an SSD.
Where as an optical drive should be able to be acquired by almost anyone who wanted to recover the data off the DVD at a later point. The ones I'm looking at have a nice printing surface (which my printer can do) and good reputation for longevity. My computer also has an optical drive that can burn them. It's a fine art printer, so I can also print the case insert with good quality color and longevity. So if we do DVDs, I can produce the physical portion of the Keepsake Collection right in my office.
I'd love discussion on this!
Come hang out in the Discord server! Just make a Discord account and click this
https://discord.gg/fv2bAVVUBQ to join. Discord can be a little intimidating, but we keep our server simple and are always happy to help people learn their way around!