Independent copies in Drive, Dropbox, and OneDrive
An independent copy would belong to the account that receives it. That feature is not in the first release.
An independent copy is a separate file in someone else's account. Google Drive, Dropbox, and OneDrive are the later targets. They are not part of the first release. OurChest does not connect them today.
When that later copy exists, it will not be the Chest. Removing the Chest will not remove the copy, and removing the copy will not remove the Chest. The guest does not choose a provider in order to join.
Joining stays a display name. There is no email address and no password. The file in the Chest is the file the phone uploaded.