So entirely unusable by any layperson, or the majori of the population.

Obviously the majority of the population needs to elect better leaders, or failing that, be out in the streets over this. But they aren't. They don't care and there lies the real problem.

The closest I've found is VeraCrypt, which is near the edge of what I'd call layperson-friendly. But if you store a VeraCrypt drive on the cloud, you'll need to re-upload the entire encrypted file--usually quite large--every time you change anything at all. That's a _lot_ of bandwidth, and likely to be quite slow to sync.

Sparsebundles