A photo index the cloud didn't build for you.
Photos are cheap; captions are the scarce resource. The captions are also what the grandchildren will thank you for.
Cloud photo services do the recognition for you and, in exchange, learn your family's faces. If you'd rather do the captioning yourself and skip the recognition, a file is the container.
Photos live in folders; the index lives in a file
Keep the photos wherever they already are — the camera roll, the family NAS, an external drive. The index points to them, adds captions, names names, and dates the undated.
Who's who
Especially for the older photos where nobody left in the family can tell you. Do this while the person who can, still can.
Printed once a year
Turn the year's photos and captions into a printed book. HTML prints properly; that's the moment the file becomes an object.
What to reach for
Common questions
Face recognition?
None — deliberately. You caption; the file remembers.
Cloud backup of the photos?
That's your choice, in whatever service you use. The index is separate — it points to files, not the other way round.
Multiple photographers in the family?
Shared file in a shared folder; anyone captions.
For inherited photos?
Especially for those. The moment the person who remembers is gone, the caption becomes unrecoverable — write it now.