Have you heard of [syncthing](https://syncthing.net/) ? It syncs a folder between devices, like Dropbox, without the need for someone else's computer. No cloud, it's just your pc talking to your phone, directly and automatically, through your home WiFi.
All said and done… people should have personally controlled access to their data. For physical things, some people have safes, others use safety deposit boxes at banks. But we don’t have a digital equivalent. And the problem is that the complexity is too high for a lot of people. So something like this would be good for some people, it still won’t get the majority. What we need is the digital equivalent of a fiduciary. Someone who is legally bound to look out for a person’s digital interests. That would allow people to trust such a person to vet simpler wrappers around set ups like this, or anything.