Files: Filerun or File Browser both allow upload and download. I prefer the former as it allows me to preview file contents more broadly (e.g. pictures and videos). But it is paid.
Calendar: DecSync or Radicale both have no web UI. I prefer the former because it doesn't need a server at all, just a file sync solution. But, if you have an iPhone there are no clients and you'd have to setup a radicale server anyway.
Notes: Like others have said, Obsidian with Obsidian-livesync.
The nice thing about Filerun/DecSync/Obsidian is they store or serve files in close to their original format (e.g. files/xml/plaintext), so you can still open the file up on any computer and read its contents the way you normally would.