So here's a pretty weird idea I had: the best place to backup personal data is AWS S3 (or a similar Azure/GCP offering). It's the safest, most durable, most secure, and—here's the weird part— the *most private* data storage solution.
I’ve been using Arq + S3 infrequent access tier for backups for years. It’s great! https://arqbackup.com
I have Arq encrypt everything on-device, so I only take advantage of S3’s durability and availability. I suppose backing storing the key in S3 gives the same property.