Ironically, the mobile app allows you to "scan" barcodes and export lists via email. If you scan 100 books, you can email yourself the CSV. This is the closest thing to a "physical downloader."
WorldCat.org is the world’s largest network of library content and services, containing millions of bibliographic records for books, theses, dissertations, audiovisual materials, maps, and digital archives. While WorldCat provides excellent discovery and citation tools, researchers, librarians, and data scientists often require bulk or structured access to records for offline analysis, metadata enrichment, or local system migration. worldcat.org downloader
The WorldCat.org Downloader is a command-line tool and Python library designed to automate the retrieval of bibliographic metadata from WorldCat’s public interface. It respects robot exclusion rules, uses efficient request throttling, and outputs data in standard formats (MARC21, MARCXML, JSON, CSV, or BibTeX). This tool is not affiliated with OCLC and is intended for fair use, non‑infringing purposes. WorldCat
This is the most common form of "downloading" on the platform. If you are writing a thesis or managing a reading list, you can download the record of the item. uses efficient request throttling
Zotero is a citation manager. Its browser extension detects WorldCat pages.