As a long-term user of Synology NAS, I already have one central solution to store all photos and videos, a Diskstation 918+ with 10TB storage. The NAS has a "photos" folder, all important family members have accounts and can store all photos in that folder. It's organized by year and one folder for each event.

When I first set up that photo solution I feared that no one would like to use it, but everyone liked the idea to have one central storage for all photos where everyone can also see and download the photos of others.

To make sure this is not the only place where everything is stored, I have another, older NAS sitting at my mom's house that is used as a remote backup solution. If ever comes the situation that both my and my mom's NAS are destroyed, photos probably don't matter anymore, so that's totally fine for me.

Of course, two NAS with much storage is quite expensive, but I guess it's cheaper in the long term, than paying for a multi-TB cloud storage every year.

TLDR: two NAS at different locations, one has a shared folder where all family photos are stored, one is backup only.