using n/sftp if I download a CSV file, am I able to iterate it and work with it without first saving it to the filecabinet and re-loading it? I want to validate various details before committing it to the filecabinet, tricky to test. I suspect I can but be good to know in advance.

Yes, a file can be read, updated, and deleted without creating a file record for it in the file cabinet.

Perfect, thanks @mattdahse for confirming.