I'd just buy them a PAIR of hard drives to back up all their cellphone pictures, then in addition: an online cloud backup plan, say for a 5 year term(to start, they pay after that). Then TEACH THEM HOW TO USE BOTH!
A friend of mine just "lost" about 15,000 photos she has taken over the past 5 years or so, mostly on her Iphone. She was devastated. Unfortunately, she had NO BACKUP PLAN, and now only has social media(IG/FB) to rely on for the pictures she has actually posted there.
With film, you had negatives as a backup plan, if the prints were lost/damaged. Now with digital, a solid backup plan to save digital files is IMPERATIVE, if you want to reprint/save those digital files, which can easily get lost/damaged/corrupted if you simply look at the device wrong.
Forget the tech, the parents won't want to futz with a camera, they'll use a cell phone most likely. Go with the backup plan, especially one that's locally-stored, but also backed up on the cloud.
Just my $.02
-Dan