Looks very exciting, especially the fact that some of these services will be self-hostable!
I'm curious about Thunderbird Send: if it's end-to-end encrypted but shared without a password, how are anonymous clients able to decrypt the file contents, but the Send server is not? Is the decryption key stored in the URL (and not persisted/logged on the server)?

Edit: looks like this is partially discussed around 42 minutes in, but I'm not sure how it works for password-free files.