SnipNotes does not save your notes as files, but as data records in a database called CloudKit. This is a delimited area within iCloud that is not displayed in the file browser. Within this database, each app has its own container that only it can access.
As the notes are not saved as files, I unfortunately cannot easily synchronize them with a file-based provider such as Dropbox or Nextcloud. To do this, I would have to completely redevelop the storage format and unfortunately there is not enough demand for this.