This sounds like a cool idea, I'd be of little use but it seems like a great way of a sort of history record of milestones on omni.

And possibly if there's a demand, we could make physical yearbooks from the digital one? (on a case-by-case basis, obviously)

I don't know how easy this will be to do, but this sounds like a good idea to me.
Digital distributions seems the easiest and best solution to me and if you'd really want it physically, you can get it printed yourself

Digital distributions seems the easiest and best solution to me and if you'd really want it physically, you can get it printed yourself

It depends. If the yearbook includes gifs or even videos, you won't be able to print it
Otherwise, yes, making it digital also allows a paper version