Thought of something like this a while ago.
A wedding event app to share guest photos with the bride and groom and also put up the photographers pics there after the event for guests to access. Avoiding the friction of sharing lots of photos across iOS/Android or having them all downscaled sending by messenger apps.
Put QR codes on the tables and guests can access an Insta style feed and upload their own pics to it, can stream it on the screens too.
Asians would go nuts for this.