Bitwarden also does not currently export attachments (which, in practice, is more of an issue for vault backup workflow than for shuttering one’s account) — however, there is a feature request here. Nonetheless, through the CLI client, it is possible to script the download (and upload) of attachments; one example of this is the third-party tool Portwarden.
And yes, all attachments are stored in the cloud as encrypted blobs.