Honestly if they are not that technical, I’d with the nearly fool proof solutions of QNAP and Synology and alike. It is very easy to maintain. I think e.g. Synology still provides updates for their 2012-2013 generation devices, hardware limitations apply whatsoever.

Surely you get less Hardware/Dollar but the software is near fool proof. I recommended such devices to two of my half technical friends and granted mutual space for encrypted off-site Backups and it just works flawlessly. If they would have me setup any self made raspberry pi like solution and anything goes wrong with their data I’d rather not stand in their line of sight.