I don’t think site security is the main concern for the average person when it comes to this use case. They run the same risk with all of their physical possessions and there are existing solutions for this eg firesafes. Making sure that drive failure doesn’t wipe out your photos or files would be more important. Multiple redundant drives are the solution. If each is a small SSD and plug and play it’s something anyone could handle by just buying a new drive and swapping it out. Physical data appliances need to be as simple as a lamp. Plug it in, turn it on and occasionally replace a light bulb.

Or use encrypted mutual backups on others like systems (eg you friend buys the same model and you each clone each other’s, transparently, securely). Storage is cheap so you just over provision the space so that it can be both super durable, and have space to backup friends’.