If you're interested in an open source, (including the server) self hostable, E2EE and federated/p2p storage, sharing and app protocol (including calendar, docs etc) who doesn't have VC investors, check out Peergos:
We treat the server as an adversary. So everything is chunked an encrypted so the server can't see file data, filenames, file sizes, whether something is a file or dir, who has access to a file, who your friend are etc. Everything is signed so servers can't tamper with your data either.
We also use a p2p and self-authenticated protocol so it is easy to migrate servers whilst keeping your identity, friends and data.
Interesting, in selfhosted discussions, I usually hear about that as a negative (it comes up frequently in the seafile - nextcloud comparison). It makes sense, but I hadn’t heard the pro-part of the argument before.
I can highly recommend this system. Have been using it for years now, since it was alpha - for sensitive data and for any other data, instead of things like Dropbox or G-drive. Convenient, easy, safe. Thanks!