What are you celebrating?
It does not have to be a birthday. Anything worth marking properly works the same way: your photos, your music, your words, and messages from everyone else.
Anniversary pages
Anniversaries are the hardest to buy for, because the whole point is that the thing you already have is the gift. A page does not try to compete with that. It just shows it back to them.
Valentine's Day pages
Valentine's has an unusually low bar and an unusually high price. A restaurant charging double for the same menu is not romance. Something made specifically for one person is closer to the idea.
Mother's Day pages
The problem with Mother's Day is that everyone sends something separately, so she gets four nice messages spread across four apps. A page collects all of it into one place she can open again.
Graduation pages
A graduation is one of the few days where the achievement is genuinely theirs and everyone else was only watching. A page is a way for the watching to be said out loud, by all of them, at once.