> One thing I've actually not seen is E2E contacts & calendars. Everything seems to be based on CalDAV & CardDAV which I think forces you to sync them with a server in plaintext. Email is mostly a lost cause, the closest you could approach it is something like protonmail AFAIK.
Totally agree. I think the natural progression of things to replace would be contacts and then calendaring. For the life of me, I can't figure out what should/how to replace email. Or simply make it more secure for the masses.