In uk.comp.os.linux Rich wrote:
Another item that has not been mentioned yet is git annex:
https://git-annex.branchable.com/

I've been meaning to look at that for a while. It does seem interesting in
that it supports protocols like Google Drive for storing files. However, I
don't know if they're usable on Android/etc if encrypted - you just have a
pile of encrypted files and hashes.

There's an Android app:
http://git-annex.branchable.com/Android/
and a git-annex based FS (a bit old):
https://github.com/chmduquesne/sharebox-fs
but otherwise it seems like any encrypted system needs a client at the other
end, and that doesn't exist for all platforms.

Theo